Half the messages used to output 'id[%name]' and half id[%name]. With
this change, all messages consistently output 'id[%name]'. Some typos
are also fixed in the process.
* Moved function opcode validation out of idUsage and into new files
* minor style changes
* General opcode checking is in validate_function.cpp
* Execution limitation checking is in
validate_execution_limitations.cpp
* Execution limitations was split into a new pass as it requires other
validation to register those limitations first.
