Use atsign-simd for sum
initial implementation of call overloading: f(x...) gets turned into call(f, x...) as a fallback (if f is not a function); to do: update inference, fallback to call when f is a type
make sure call passes through keywords
fix call overloading for type constructors, add some tests
support generic call in apply(f, ...)
(broken) patch to eliminate emit_func_check
get basic call overloading working with 1 bootstrap stage
Merge branch 'master' into call_overload

Conflicts:
	src/codegen.cpp
	test/core.jl
update emit_call for jl_fptr_llvmt => jl_pfptr_llvmt change
Add arm specific configuration to help in the port.
Makefile changes to build on ARM
Add fake cpuid for ARM

TODO: proper implementation using procinfo
arm: use LLVM3.5
Rename Make.inc.arm to ARM.inc
Add checksums for llvm 3.5.0
Add basic ARM README
ARM.inc should have lower precedence than Make.user
Reorganize Make.inc to do detection earlier
add checked_{add,sub,mul} for BigInt
fix #5935 (rationalize returns curious/incorrect values)

Partially addresses #7501.