Use Doubles for Pixel Representation

[viluon]

Profiling has shown possibilities for an increase in performance and a major decrease in memory usage when using doubles instead of tables for pixel representation. Certain checks, such as the recently implemented (but not yet pushed) #14 are no longer relevant, as generated doubles are actually equal if their "arguments" are equal. Doubles also mean much less stress on the garbage collector.

This change means a major overhaul of desktox.buffer. To fix #10, we will actually only need to implement a small set of :import()able methods. Buffers will be able to act both in pixel-perfect and terminal ways, and will easily switch between the two without any constructor calls.

[viluon]

To fix #10, we will actually only need to implement a small set of :import()able methods.

Moreover, one can use the pixel-perfect methods for caching common pixels and thus avoiding some pixel creation operations.