Label: Rename class to Text
Texture: Bit of clean up (re-organization)
Text: Implement getters for variable texts for size calculations

* Remove NOM_DEBUG_TEXT preprocessor define
Text: Implement preliminary support for \v & \t characters
SDL_helpers: Move ticks function wrapper to system/Sleep
system/Sleep: Rename to sleep
examples/app: Fix sprite rotation slow down

* We were calculating the sprite’s rotation angle by variable FPS, hence
why we noticed jitter when frame rate varied greatly.
Sprite: Clean up err handling a bit inside load method
Text: Fix indention level
Image: Implement getter for creating texture from its surface
Texture: Make method calls done inside load method re-usable

* Rename Access::RenderTexture to Access::RenderTarget
* Remove initialize(SDL_Surface*) method
* Re-order the arguments of the initialize method for non-static Textures
* Introduce create methods for initialization from a nom::Image object
* Rename update method arguments
* Introduce copy_pixels method (std::memcpy with err checks)
Renderer: Move update(SDL_TEXTURE*) to Texture

* Introduce reset method for Renderer
IFont: Change return type from SDL_Surface* to const Image&
Image: Fix indention
Image: Remove const from getters of basic int types

* const does nothing for us