* always write the mtime to a .pyc in little endian format
 * ensure class's docstrings get attached to the class, not the
   enclosing scope!

Rather more fixes are needed for the trunk; these will be done in due
course.

'release22-maint'.

Fix by Neil Schemenauer.  Visit the Subscript node when trying to find
the operation for a statement.

XXX Not sure if there are other nodes that should be visited.

There are now no known cases where the compiler package computes a
stack depth lower than the one computed by the builtin compiler.  (To
achieve this state, we had to fix bugs in both compilers :-).

The chief change is to do the depth calculations with respect to basic
blocks.  The stack effect of block is calculated.  Then the flow graph
is traversed using breadth-first search to find the max weight path
through the graph.

Had to fix the StackDepthTracker to calculate the right info for
several opcodes: LOAD_ATTR, CALL_FUNCTION (and friends), MAKE_CLOSURE,
and DUP_TOPX.

XXX Still need to handle free variables in MAKE_CLOSURE.

XXX There are still a lot of places where the computed stack depth is
larger than for the builtin compiler.  These won't cause the
interpreter to overflow the frame, but they waste space.

compile() becomes replacement for builtin compile()
compileFile() generates a .pyc from a .py
both are exported in __init__

compiler.parse() gets optional second argument to specify compilation
mode, e.g. single, eval, exec

Add AbstractCompileMode as parent class and Module, Expression, and
Interactive as concrete subclasses.  Each corresponds to a compilation
mode.

THe AbstractCompileMode instances in turn delegate to CodeGeneration
subclasses specialized for their particular functions --
ModuleCodeGenerator, ExpressionCodeGeneration,
InteractiveCodeGenerator.