Start working on program_options, add arg class
Add the internal details used by the command line parser
Fix issue with GEARS_NO_IOSTREAM missing
Make details inline to fix ODR issues and add special case for lexical_cast
Add initial program_options class for parsing command line arguments
Add support for default values with override semantics
Add named parameter for default value
Fix bug with some command line options not overriding
Add missing const and noexcept qualifiers to lines
Made program name configurable rather than assuming it's argv[0]
Redesigned exception to be invalid_arg_get rather than arg_not_found
Add support for required arguments
Add error for unrecognised arguments
Provide default program name
Add ability to add with arg class instances, made required named parameter default to true
Add basic math algorithms
Normalised spaces for program_options again
Start providing some basic ADL functions
Add swap ADL function
Add get ADL function