Changes to eliminate compiler warnings on MSVC

This code was not compiling under Visual Studio 2013 with warnings being treated
as errors. Specifically:

1. Changed int -> size_t to eliminate signed/unsigned mismatch warning.
2. Added some missing return values to functions.
3. Inserting character instead of integer literals into strings to avoid type
   conversions.

A=cmumford
R=jeff
1 file changed