Implement cld
Document cld
Fix hangs and segfaults when egregiously long symbol is used.
Check nb instead of length.
Add tests to catch regressions in code_native and code_llvm.
Add tests for isbits.
Add a bit more explanation.
make `big` map ranges to ranges
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.
Merge branch 'arm-make3' of github.com:JuliaLang/julia into arm-make3

Conflicts:
	Make.inc