implemented the #pragma once to the compiler

[grivetti]

What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes issue #419

What kind of pull this is:

• A Bug Fix
• A New Feature
• Some repository meta (documentation, etc)
• [ x] Other

Additional Documentation:

Changed the compiler to accept the "#pragma once", also changed the include folder as well to the new feature

[Y-Less]

How is this different to #463 ? Does it address the issues raised there? And why are there 4000+ lines changed in sc2.c?

[grivetti]

In the parte of the 4 thousand lines changed, I really don't know How that happend, I only changed some

[Y-Less]

I suspect it was just some auto-formatting from your editor.

[YashasSamaga]

"... to merge 1 commit into pawn-lang:master from"

master or dev?