v1.2.0: Custom help (#50)

* Finishes addressing issue #29

Adds a Settings struct for creating parsers/commands with
NewParserWithSettings or NewCommandWithSettings.

Settings
	HelpDisabled -	defaults false, set true to not generate a help
			argument for parser/command
	HelpSname -	short name for the parser/command help argument.
			Can be left empty
	HelpLname -	long name for the parser/command help argument.
			Leaving empty forces use of -h/--help when
			HelpDisabled is false
	NoExitOnHelp -	defaults false, set true to not exit on help
			argument being parsed

Should resolve all outstanding help argument issues.

* Finishing Issue #29

Fixed merge conflict error due to check function return type change confusion.

* Updated Settings Object to multiple function calls

Added functions:
	DisableHelp
	SetHelp
	ExitOnHelp

Added Command.exitOnHelp

Added more tests to increase code coverage

* Updated no help example