not just numerics as before.

fixes #628

Fixes #607 (not really, but it was fixed already, probably in https://github.com/RDFLib/rdflib/commit/acc6ed3e3548a75541607ec753d05d5061028465

This was the same error as #580, but for SubQueries instead of binds.
Same fix as
https://github.com/RDFLib/rdflib/pull/688/commits/c1b29aea3803e6e25287cfdf794f030538bdfa7c

Excempt vars bound in the local scope from forgetting.

Made Extend eval only forget vars not bound outside.
Made Extend only collect vars not in "expr"

This fixes #580

Fixes #615
Also adds unit tests.

The original data-r2 files came from the jena repository, they included a handful of changes to make the data-r2 tests in line with SPARQL1.1 - these changes have been kept, the diff is below:

diff --git a/test/DAWG/data-r2/basic/data-4.ttl b/test/DAWG/data-r2/basic/data-4.ttl
index bfd42b7..5598d40 100644
--- a/test/DAWG/data-r2/basic/data-4.ttl
+++ b/test/DAWG/data-r2/basic/data-4.ttl
@@ -8,7 +8,7 @@
 :x rdf:type :C .

 :x :n1  "123.0"^^xsd:decimal .
-:x :n2  "456.0"^^xsd:decimal .
+:x :n2  "456."^^xsd:decimal .

 :x :n3 "+5"^^xsd:integer .
 :x :n4 "-18"^^xsd:integer .
diff --git a/test/DAWG/data-r2/basic/manifest.ttl b/test/DAWG/data-r2/basic/manifest.ttl
index b0e0f06..4306319 100644
--- a/test/DAWG/data-r2/basic/manifest.ttl
+++ b/test/DAWG/data-r2/basic/manifest.ttl
@@ -30,8 +30,8 @@
       :term-3
       :term-4
       :term-5
-#      :term-6 # Not SPARQL 1.1
-#      :term-7 # Not SPARQL 1.1
+      :term-6
+      :term-7
       :term-8
       :term-9

diff --git a/test/DAWG/data-r2/basic/term-6.rq b/test/DAWG/data-r2/basic/term-6.rq
index a03be7e..617c296 100644
--- a/test/DAWG/data-r2/basic/term-6.rq
+++ b/test/DAWG/data-r2/basic/term-6.rq
@@ -2,6 +2,4 @@ PREFIX :     <http://example.org/ns#>
 PREFIX xsd:  <http://www.w3.org/2001/XMLSchema#>

 # DOT is part of the decimal.
-#SELECT * { :x ?p 456. }
-#SPARQL 1.1
-SELECT * { :x ?p 456.0 }
+SELECT * { :x ?p 456. }
diff --git a/test/DAWG/data-r2/basic/term-7.rq b/test/DAWG/data-r2/basic/term-7.rq
index 74d98f7..61d1d03 100644
--- a/test/DAWG/data-r2/basic/term-7.rq
+++ b/test/DAWG/data-r2/basic/term-7.rq
@@ -2,4 +2,4 @@ PREFIX :     <http://example.org/ns#>
 PREFIX xsd:  <http://www.w3.org/2001/XMLSchema#>

 # DOT is part of the decimal.
-SELECT * { :x ?p 456.0 . }
+SELECT * { :x ?p 456. . }
diff --git a/test/DAWG/data-r2/expr-builtin/manifest.ttl b/test/DAWG/data-r2/expr-builtin/manifest.ttl
index ae1431f..1bd646d 100644
--- a/test/DAWG/data-r2/expr-builtin/manifest.ttl
+++ b/test/DAWG/data-r2/expr-builtin/manifest.ttl
@@ -11,10 +11,7 @@
     rdfs:comment  "DAWG Expression tests: Built-ins" ;
     mf:entries
     ( :dawg-str-1 :dawg-str-2 :dawg-str-3 :dawg-str-4
-      :dawg-isBlank-1 :dawg-isLiteral-1 :dawg-datatype-1
-      ## remove test - chnages for SPARQL 1.1 and RDF 1.1 (rdf:langString)
-      ##:dawg-datatype-2
-      :dawg-datatype-3
+      :dawg-isBlank-1 :dawg-isLiteral-1 :dawg-datatype-1 :dawg-datatype-2 :dawg-datatype-3
       :dawg-lang-1 :dawg-lang-2 :dawg-lang-3 :dawg-isURI-1
       :dawg-isIRI-1 :dawg-langMatches-1 :dawg-langMatches-2
       :dawg-langMatches-3 :dawg-langMatches-4 :dawg-langMatches-basic
diff --git a/test/DAWG/data-r2/manifest-evaluation.ttl b/test/DAWG/data-r2/manifest-evaluation.ttl
index 70e3f4d..5f7193b 100644
--- a/test/DAWG/data-r2/manifest-evaluation.ttl
+++ b/test/DAWG/data-r2/manifest-evaluation.ttl
@@ -26,8 +26,7 @@
         <expr-ops/manifest.ttl>
         <expr-equals/manifest.ttl>
         <regex/manifest.ttl>
-    # Needs the data parser fixing (less strict)
-       # <i18n/manifest.ttl>
+        <i18n/manifest.ttl>

         <construct/manifest.ttl>
         <ask/manifest.ttl>
diff --git a/test/DAWG/data-r2/optional-filter/manifest.ttl b/test/DAWG/data-r2/optional-filter/manifest.ttl
index f7a5f7b..1b1d977 100644
--- a/test/DAWG/data-r2/optional-filter/manifest.ttl
+++ b/test/DAWG/data-r2/optional-filter/manifest.ttl
@@ -8,14 +8,7 @@
 <>  rdf:type mf:Manifest ;
     rdfs:comment "OPTIONAL with inner and outer FILTERs" ;
     mf:entries
-    (:dawg-optional-filter-001
-     :dawg-optional-filter-002
-     :dawg-optional-filter-003
-     :dawg-optional-filter-004
-    # The extra two are mutually exclusive : same query, same data, diferent reading of spec.
-    # ARQ implements the intent: simplify after all algebra generation done.
-    #:dawg-optional-filter-005-simplified
-     :dawg-optional-filter-005-not-simplified).
+    (:dawg-optional-filter-001 :dawg-optional-filter-002 :dawg-optional-filter-003 :dawg-optional-filter-004 :dawg-optional-filter-005-simplified :dawg-optional-filter-005-not-simplified).

 :dawg-optional-filter-001 a mf:QueryEvaluationTest ;
       mf:name    "OPTIONAL-FILTER" ;
diff --git a/test/DAWG/data-r2/syntax-sparql1/syntax-lit-08.rq b/test/DAWG/data-r2/syntax-sparql1/syntax-lit-08.rq
index d780dc3..04fd35e 100644
--- a/test/DAWG/data-r2/syntax-sparql1/syntax-lit-08.rq
+++ b/test/DAWG/data-r2/syntax-sparql1/syntax-lit-08.rq
@@ -1,11 +1,3 @@
 BASE   <http://example.org/>
 PREFIX :  <#>
-#SELECT * WHERE { :x :p 123. . }
-
-# SPARQL 1.1
-SELECT *
-  {
-      :x :p1 123.0 .
-      :x :p2 123.  # SPARQL 1.1 -- integer
-      :x :p3 123.
-  }
+SELECT * WHERE { :x :p 123. . }