v2.09 Released

Fix olc::Renderable Image load error - Thanks MaGetzUb & Zij-IT for finding and moaning about it
Fix file rejection in image loaders when using resource packs
Tidied Compiler defines per platform - Thanks slavka
+Pedant fixes, const correctness in parts
+DecalModes - Normal, Additive, Multiplicative blend modes
+Pixel Operators & Lerping
+Filtered Decals - If you hate pixels, then erase this file
+DrawStringProp(), GetTextSizeProp(), DrawStringPropDecal() - Draws non-monospaced font