Added APIs and core functionality

The Graphics API and the TableUtils API were added which contain
graphical
functions/constants and functions related to table manipulation.

Also, the Pixel and ScreenBuffer classes were added which support the
concept
of switching between threads in that each thread saves a copy of the
buffer
before being switched out. When the thread is switched back in, it sets
the buffer to its copy of the buffer's old state.

Also, the ProgramManager program was updated a little bit to work with
the ScreenBuffer.