Made small optimizations to Texture's SetRegion, SetLinearRegion,
GetRegion and Clear. They might not be super effective depending on how
the compiler already optimized them. The optimizations mainly focus on
removing the multiplication when transforming a position to an index by
using the row index rather than the y coordinate during iteration.
Also fixed regions not drawing properly when clipping against the sides
of a window and made GetRegion reject any region that isn't fully inside
of the window (previously accepted regions that clipped outside of the
right and bottom side, possibly leading to incorrect reads on the user
end due to desynchronized region dimensions)
Fixed an annoying bug where the application would freeze when resizing
the window
This pull request made it so the SDL window's resizing event now
broadcasts a new event specifically asking the swapchain to recreate
itself, which will in turn broadcast the original event when done. It
also removed the Event enum specific values, as they were irrelevant.
