Add disassembly to machine code

- FuncMCView wraps the memory block in MemoryObject interface.
- The slightly tricky thing is to get the in-memory size of the final
asm. This is not exposed by the ExecutionEngine, but conveniently it is
stored already in jl_jit_events FuncInfo structure.
- Uses MCDisassembler, implementation directly derived from code in
llvm-mc.
delete / out of order dequeue on PriorityQueue
added tests for priorityqueue dequeue out of order
Correct beta function for negative arguments. Correct documentation for lgamma and lbeta. And some tests.
Merge pull request #3290 from JuliaLang/anj/fixmath

Correct beta function for negative arguments.
small optimization to bitarray getindex
Merge pull request #3284 from ihnorton/disasm

RFC: Add disassembly to machine code
isprime: fix precedence bug.
fix endof(SubString) and write(io, SubString)
Merge branch 'master' of github.com:JuliaLang/julia
throw KeyError on nonexistent key
syntax error for ccall used as an identifier. ref #3289
Merge pull request #3286 from tanmaykm/tanmaykm

delete / out of order dequeue on PriorityQueue
error for global or local in value position. fixes #3271
Merge branch 'master' of github.com:JuliaLang/julia
pkg resolve: tighten return type, use sortby instead of Sort.By
pkg2: hook new query infrastructure up to old resolve mechanism.
Merge branch 'master' of github.com:JuliaLang/julia
pkg2: expose ability to add and rm package requirements.

This should ultimately also call resolve and provide transactions.
fix #3293, do block inside function argument