Use less generic names for variables.

These are generic enough that in libcxx, they get expanded into
functions which also have variables named the same thing (__x, __y)
and that then leads to a buggy libcxx.
Fix the return value of fgets().
support -s KEY=@PATH in emcc, for very large settings values
update test_chunking
unique ids for aborts for dead functions
fix globalScope altering in runtimelink modules; fixes test_runtimelink
make sure SDL.channelMinimumNumber is initialized; fixes SDL audio tests
make test_sdl_audio_mix report a result
infrastructure for implementing i64 math in asm.js, and implement i64Add and llvm_uadd_with_overflow_i64 that way
optimize pread to use typed array set()
headless improvements
Merge pull request #942 from waywardmonkeys/fix-typeof-decls

Use less generic names for variables.
write strcpy in asm and add some testing
asmify strncpy
fix test_relooper
disable EMCC_DEBUG when bootstrapping relooper
use memory a little more efficiently in emscripten.py
turn calls to undef into aborts, so they asmify
Merge branch 'incoming' of github.com:kripken/emscripten into incoming
optimize memory use of funcs_js in emscripten.py