Added Texture Unit Saving

Shader programs now store what texture unit and texture you are
associating a sampler uniform with.
Handle Texture Unit With Texture Already Assigned

It will replace that unit's texture and uniform location with the new
info.
Added OpenGL Version Requests

The new Pancake constructor takes the version of OpenGL a user would
like to request.
Added Files To .gitignore

I don't need it to track my todo list or user settings
Fixed .gitignore

Had to remove the explicity directories to get it to ignore the files
Created Context Class

This class will handle creation and memory management for OpenGL
contexts.
Added setActive Method To Context

Sets the context to either active or inactive.
Added Context Creation

The Context class can now create itself for a specific window and GL
version.
Added Error Checking

Context::setActive() now handles errors and reports them to the user.
Added Context Checking

Contexts can be checked now as a bool to see if they're valid or not.
Changed Context::setActive()

It now takes a reference to a Window object rather than an SDL_Window
pointer.
Construct Window From Existing

Window can now take an already-created SDL_Window* and use it as its
internal window.
Make Window Non-copyable And Non-movable

Added copy/move constructors and operators to prevent these operations
on a window.
Make Context Non-copyable And Non-movable

Added copy/move constructors and operators to prevent these operations
on a context.
Added Simple Context::create()

This version takes a window and constructs the context with the
currently-set flags.
Fixed Simple Errors
Made Pancake.pro File Cross-Platform
Added ContextSettings Structure
Used ContextSettings in Context

It uses default settings so that just a Window can be passed.