Windows build fixes
Fix string_reset

Should make nused=0, not nalloc=0
Bench: don't use C++ cout/cerr (very slow)
bench: Allow multiple file inputs, and print total MB/s
t_ops: performArith should return uint16 statud
Remove non-ascii sequence to silence compiler warning

While the actual source doesn't care, it makes MSVC complain.
Allow to exit the parser once the match has been found

This allows a huge performance boost for documents which are rather
long, and where the match is somewhere in the middle, or in the
beginning - as this lets us immediately exit from the parser, and not
require us to traverse the tree!
Document additional performance characteristics