simple project type detection tool.
detect more things.
put commands to run in detect as well.
make detect a package.
add standalone test program for detect.

also, fix detect itself (relative references are ... bad?)
simple api for detect.
detect procfiles and makefiles later.
use detect in qst.

this also changes the behaviour to chdir into the directory of the file
given, which may or may not be good. but i think it makes sense for a
lot of projects.

yet, we might want to cd to the *root* of the project sometimes, but
specify a file in it. not now, but probably should keep this in mind.
remove old mappings.