The idea comes from The OpenGL Shader Wrangler
(http://prideout.net/blog/?p=11). Text files are broken up into chunks via
lines beginning with -- (^-- in regex). The chunks are optionally named
with tags of the form: [0-9A-Za-z._]+. Unnamed chunks cannot be found.
Searching for chunks looks for the longest tag that matches the beginning
of the search tag (eg, a chunk named "Vertex" will be found with a search
tag of "Vertex.foo"). Note that '.' forms the units for the searc
("Vertex.foo" will not find "Vertex.f").
Unlike glsw, this implementation does not have the concept of effects keys
as that will be separate. Also, this implementation takes strings rather
than file names (thus is more generally useful).
