Look instead for the first '<', as some test scripts add arguments after execopts
Merge pull request #119 from benharsh/stdin-in-execopts

Fix stdin execopts to look for first instance of '<'

Some of our automated tests add arguments after those in execopts, and we were only looking at the last two arguments. This fix will look for the first instance of '<', instead of looking at the second-to-last argument.
Add comments at the top of chpl-string-support.[ch] about the file and
possibly renaming of the file as well as the functions within.
Merge branch 'master' of github.com:chapel-lang/chapel into test