to be very slow.  this now has the effect of producing "conditional" unicode
conversion for the Oracle backend, as it still returns NVARCHAR etc. as unicode
[ticket:2911]
- add new "conditional" functionality to unicode processors; the C-level
function now uses PyUnicode_Check() as a fast alternative to the isinstance()
check in Python

Python ``Decimal`` via string is now configurable.  The
flag ``decimal_return_scale`` is now supported by all :class:`.Numeric`
and :class:`.Float` types, which will ensure this many digits are taken
from the native floating point value when it is converted to string.
If not present, the type will make use of the value of ``.scale``, if
the type supports this setting and it is non-None.  Otherwise the original
default length of 10 is used. [ticket:2867]

- went through examples/ and cleaned out excess list() calls

- repair test_processors which wasn't hitting the python functions
- add another suite to test_processors that does distill_params

This breaks backwards compatibility with old SQLite DATETIME, DATE,
and TIME storage_format strings. Formatting now occurs with named instead
of positional parameters. The regexp argument can still use positional
arguments, but named groupings are also supported. This means that you can
omit fields and change the order of date fields as desired.

SQLite's DATETIME and TIME also gained a truncate_microseconds argument.
This is shorthand for modifying the format string. Fortunately the
str_to_datetime and str_to_time processors written in C already support
omitting microseconds, so we don't have to resort to python processing
for this case.

or invalid string is passed to any of the
date/time processors used by SQLite, including
C and Python versions.  [ticket:2382]
- changed the import model of processors.py so that we can
get at the pure python versions and C versions simultaneously
in tests.