Restructure files

pbhelper is now conversion/pbbinary
Address issues with custom types and repeated/packed

Fixes issue #4
Address issue with repeated string
Add underscore to end of reserved words used as field
Correct naming for access functions
Merge pull request #5 from JesseKPhillips/customUsage

Custom usage
Merge pull request #6 from JesseKPhillips/reservedWords

Reserved words