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
Fix hang/incorrect result for ndigits with b < 0.
Remove debug junk
Add tests for ndigits (issue #8266).
Move negative base check inside ndigits0z and add a test for (unsigned, signed) case.
ndigits: don't take abs(n) if b < 0.
Throw error when bigint ndigits has a negative base.
Merge remote-tracking branch 'julia/master' into ndigits_hang
Replace 'manual' cld with cld function now that #8111 has been merged.
Match previous ndigits0z interface.
reworked cluster manager interface
Call 0z version of ndigitsnb, which avoids an extra branch.