Cleanup and new optimizations in WPython 1.1

The first WPython alpha, that was presented at the last PyCon, thanks to the word representation (called wordcode) has built the basis for a series of optimizations to the CPython 2.6 code, which permitted to get notable performance gains.
After one year WPython 1.1 shows itself as a more mature project, which has involved rewriting "non-immutable" constants code (such as for constant lists and dictionaries), making it "less invasive" towards the CPython object model.
At the same time some opcodes were reorganized, grouping together some less used and more complex ones, leaving the most frequent and common to specific instructions to improve execution speed.
Some instructions were added to satisfy some Python code patterns, whereas others were optimized for specific cases (such as for slices). Moreover, where the context made it possible, some useless controls were removed (on list comprehension and garbage collector appends, for example).
The peephole optimizer was moved in compiler.c considerably simplifying the code thanks to the internal instr structure usage, which let an easier opcode manipulations (particularly for the jump ones).
Finally, an entire new "experimental" opcodes family was added to handle binary operations cases where at least one data is an integer.