*: initial implementation of pig

This is nothing to write home about, but it provides a little sandbox for
developing shader-generated textures in the spirit of shadertoy or the
demoscene tool bonzomatic.

It's more oriented towards developing shaders for use with libstage in
the small games I've been hacking on.

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+pig is a tool to assist developing shaders for games
+
+at this time it targets just gl2.1 and is fairly minimal,
+it expects you to supply the vertex shader and fragment shader
+paths on argv as such:
+
+```
+	./pig path/to/vertex-shader path/to/fragment-shader
+```
+
+If the files don't exist or are otherwise unusable, pig will just
+skip running the shader but continue drawing a checkered bg with
+the variables changing as usual.
+
+The set of uniforms pig wires up to the shaders are currently:
+
+```
+	uniform float alpha;
+	uniform float time;
+	uniform float T;
+	uniform vec3 color;
+	uniform float seed;
+	uniform float rand;
+```
+
+alpha:	is always 1.f currently, this comes in by virtue of libstage integration.
+	when your shader is used as a shader-node w/libstage for instance, this
+	value would reflect stage_t.alpha, set via stage_set_alpha() or at stage_t
+	create time via stage_conf_t.alpha.
+
+time:	time since program start in seconds.fraction
+
+T:	0.f - 1.f, cycled at 1HZ, intended for driving animation/effects.  The
+	time uniform can be considered absolute time, whereas this would be
+	relative to the shader's start, with a duration assumed of 1 second.
+	In the future there will probably be flags or something to set the
+	duration and range.
+
+color:	a random color, randomized every cycle of T
+
+seed:	a random seed, randomized every cycle of T
+
+rand:	0.f - 1.f, a random number, randomized every run of the shader