PLUGIN_README

Plugin developer and/or hacker README:

The xref-tools directory contains a set of the standard usable plugins for DXR.
To be usable, a plugin at the least needs to contain an indexer.py file, which
is the entry point into the plugin from the indexer and web CGI locations.

If a Makefile is present, the root setup-env.sh will attempt to make the
prebuild target.

If the file set-env.sh is present, it will be sourced from setup-env.sh for use
in building. Important environment variables are:
SRCDIR     The source directory of the tree being built
OBJDIR     The build directory of the tree being built
DXRSRC     The directory that contains setup-env.sh

Note that set-env.sh is sourced in the shell, so tricks like export will work
properly.