Remove unused variable
Remove mentions of register

C++ 11 Standard (Annex D.2):

The use of the register keyword as a storage-class-specifier (7.1.1) is
deprecated.
Remove unused or undefined functions
Add required virtual destructors.
Return proper NULL delimiter

NULL will get cast to (char)0 properly, but casting ‘\0’ (technically
an int) better expresses the intent that we mean to return the
terminating char.
Fix PR comments
Merge pull request #535 from CodaFi/W-Pedantic-Warnings

Cleans up warnings