fix #5154 (nested for loop syntax & break behavior)
simpler parsing of multi-range for
Merge branch 'master' into mn/nestedforbreak
doc and test updates for `for` loop change
use filesize() for readbytes and readall on an IOStream

also decrease default initial array size used by readbytes
some updates to the (disabled) USE_MMAP code
Merge pull request #7430 from JuliaLang/mn/nestedforbreak

fix #5154 (nested for loop syntax & break behavior)