Split texture's resize function into sRGB and non-sRGB

[eXpl0it3r]

With #177 we've implemented sfTexture_resize, but the function takes a bool for switching between RGB and non-RGB, which is counter to the sfTexture_createX methods that each have their own sRGB versions.

There are two ways forward:

• Merge the createX and createSrgbX methods
• Split the resize method

I believe the reason for the separate functions are two fold:

• Adding functionality without API break
• C doesn't know of default parameter values, so method duplication is the answer

This PR chooses the method split, so one doesn't need to always provide the boolean.

[dogunbound]

Hmm, can't seem to find the approval button on GitHub mobile. This is my approval :)

[dogunbound]

Hmm, can't seem to find the approval button on GitHub mobile. This is my approval :)