added function test stub
add explicit support for stack pointer register in inferior
implemented function tracing

implemented a new session method .at_function(...) wherein the
user can specify the address of a function and prototype its
arguments. when that function is executed, mozz will invoke the
callback function with all the function arguments pulled from
the appropriate registers/stack positions and converted to python
values.

a "Convention" class must exist for the calling convention of the
binary for this feature to work. right now x86_64 sysv calling
convention is the only implemented convention.
Merge branch 'master' into function_mockups
dont do function test on non-x86_64 systems
added deref and string methods to pointer class

now testing that the string parameters are
correct in function_test
added TODO
implemented function mockups for sessions

break point starts at function entry, then the mockup function
runs, then the return value of the mockup function is used as the
return value for the mocked up function in the
the native calling convention's return procedure.
refactored Location and subclasses into location module
added to_data function to prototype.int
added set function to Int base class in prototype module

also fixed a typo
fixed typo in session module
fixed typo in abi.call module
compile test binaries with debugging symbols
added new mockup test to function_test.py

also added some helpful debug output to function_test.c
finished testing function mockup feature