Implement __aeabi_f2d and __aeabi_d2f
Merge pull request #356 from iabdalkader/d2f

Implement __aeabi_f2d and __aeabi_d2f
stmhal: Copy changes to math.c from stm port.
Fix OS X detection.

Switch to checking for the __APPLE__ and __MACH__ macros.
py/builtinmath.c: use tgamma() instead of gamma().

gamma() is now deprecated.
stmhal: Change flash MSD from fixed to removable drive.
Merge pull request #354 from xbe/osx-fix

Fix OS X detection.
Merge pull request #365 from xbe/tgamma

py/builtinmath.c: use tgamma() instead of gamma().
stm/stmhal: Change gammaf to tgammaf.
stmhal: Remove servo LED debugging.
stmhal: Improved interface to accelerometer.
stmhal: Fix issues with USB CDC init and receive.

Late USB enumeration could clear settings after they had been set.
Now fixed by not clearing some settings on init.

RX was blocking if received characters were not being processed, so
CTRL-C would not be picked up.  Now "fixed" by not blocking, but
instead discarding incoming characters if they overflow the buffer.
vm: Abstract working with tagged pointers in VM using macro accessors.

Based on issues raised during recent review and inconsistency of different
implementations.
runtime: RT_BINARY_OP_EXCEPTION_MATCH: don't fall thru in case of wrong types.
py: Implement support for "except Exception as var" clause.

For this, needed to implement DELETE_NAME bytecode (because var bound
in except clause is automatically deleted at its end).
http://docs.python.org/3/reference/compound_stmts.html#except :
"When an exception has been assigned using as target, it is cleared at
the end of the except clause."
Merge pull request #367 from pfalcon/del-name

py: Implement support for "except Exception as var" clause.