bmp files used in demos.

specifically the demos from:
  http://www.willusher.io/pages/sdl2/
Took `soe` back off of list of default things to run on `make`.
Went through lesson 2 of willusher.io demos.

Also, had attempted to fix the flickering issues in my old default
code, but at this point it seems like I need to better digest SDL2's
rendering model before attempting to put such fixes in.  I figure I
might as well jump ahead to trying to work with OpenGL instead.
Still trying random things to address flickering in accelerated mode.

Bascially am trying to adopt approaches that I saw suggested on online
discussions of changes from SDL1.2 to SDL2.0.
Initial prototype port of http://open.gl/ first triangle example.

Extended makefile a bit when I was trying to debug some problems I was
having intializing the glsl shader system.  (SDL2 is very finicky, at
least on Mac OS X, and will easily fall back into a compatibility mode
that does not support glsl version 150.)
Removed unnecessary backslash-escapes (yay Rust string literals).
Make triangle color a time-varying shade of red.

Part of this required adding an event loop.
Added color gradient between points of triangle.
make loop automatically break after 3 seconds.
Switched to using elements array to index into vertex array.
Draw a rectangle (instead of a triange), currently naively via DrawArrays.
Draw rectangle "smartly" via DrawElements.
added texcoord data (but not yet used).
First example of mixing texture (e.g. from image) into fragment shader.
Added example of mixing colors together from two input image textures.
Initial transformation code; just flips pic upside-down.
Made transformation time dependent.

This produces effect of textured rectangle rotating in the XY plane.
Attempted port of look_at and perspective and their application.

Note something is wrong with how I did look_at, but I cannot figure
out what it is.  For now I am just going to commit this work and try
to do a review of the matrix fundementals and then more direct
experimentation on what effects some adjustments have here.
Removed look_at function (presumed broken).
Alpha-rename `program` to `program1` in prep for putting in >1 program.