Fixed Preprocessors (Creator: @Redar13 )

[TBar09]

(I have gotten permission to transfer this preprocessor code into codename-dev. The creator of all this code is @Redar13 from pull request #8, with a few touching ups by me.)

Fixes preprocessors (#if #else #end) & allows for version comparing.

#if(flixel >= "5.3.0")
import flixel.sound.FlxSound;
#else 
import flixel.system.FlxSound;
#end

#if(haxe >= "4.2.5")
trace("Haxe version is more than or equal to 4.2.5!");
#end

#if EXAMPLE_DEFINE
#error "This should produce an error"
#end

The following has been changed:

• Preprocessor values set in the preprocessorValues map will be checked and accounted for; preprocessor values defined in the invalidPreprocessValues map will be considered false. The old preprocessor system only checked if the define existed.
• Version checking using ==, >, >=, <, <=, !=.
• The #error preprocessor is now usable (#error "This is an error").
• Having a preprocessor statement with an empty body no longer produces an error.
• parseString and parseModule now double checks the preprocStack for any lingering unclosed preprocessors.