Added DXF R2000 vector text.

Added SVG vector text.

Apple clang fixes

Now much more inline with how CPython does types.

OSX: fixes to make nlrx64.S with Apple's clang (switched to Apple-specific define instead of __llvm__)

Implements list.count. Fixes isue #55.

tests/bytecode/run-tests already uses puthon3.3, so let's just use it here
too.

Fore reference, errors with python 3.2.3:

  File "tests/generator1.py", line 12
    return None
SyntaxError: 'return' with argument inside generator

  File "tests/list_clear.py", line 3, in <module>
    x.clear()
AttributeError: 'list' object has no attribute 'clear'

etc.

Qstr's are now split into a linked-list of qstr pools.  This has 2
benefits: the first pool can be in ROM (huge benefit, since we no longer
use RAM for the core qstrs), and subsequent pools use m_new for the next
pool instead of m_renew (thus avoiding a huge single table for all the
qstrs).

Still would be better to use a hash table, but this scheme takes us part
of the way (eventually convert the pools to hash tables).

Also fixed bug with import.

Also improved the way the module code is referenced (not magic number 1
anymore).

With MICROPY_EMIT_X64 and MICROPY_EMIT_THUMB disabled, the respective
emitters and assemblers will not be included in the code.  This can
significantly reduce binary size for unix version.

str slice: Trim slice indexes to be in range.

Implemented list.copy. Fixes issue #54.

Use the storage cache not only for writing but also for reading. This
avoids reading stale data and thus data loss.

Implement basic slice object and string slicing

Added list.clear. Fixes issue #53.

Only step=1 and non-negative indexes are supported so far.