Convert plRegistryNode stuff to plString.
Fix issues pointed out in code review.
Fix memory leaks.
Merge pull request #254 from zrax/plstring-replace

Add plString::Replace
Merge pull request #253 from zrax/plString

Fix a major plStringStream bug, and add an SSO-like optimization to it.
Fix format string here.
Some fixes to make it all compile.
Merge pull request #251 from dpogue/plresmgr-strings

Convert plRegistryNode stuff to plString.
Add plFileName string specialization for filename manipulation
Clean up some strncats and/or replace with safer alternatives
Replace strcat with safer alternatives wherever possible