Minimize the scope of some string consts

Help prevent "duplicate symbol" linker errors when this code is included more than once in an app (because one or more libraries includes this code).
And...two more potentially duplicate symbols fixed
oops - fix typos
Allow project prefix for all public symbols
Seems to be a day for typos...
Use #defines to prevent duplicate symbol conflicts
tidy up a bit
Merge pull request #137 from dgoldman-ebay/master

Minimize the scope of some string consts