patches to env_set

define ROOMU_SYS by audodetecting the root directory in the env_set
script if possible.  if autodetect is not possible, print error.

prepend ROOTSYS/lib to ld_lib_path instead of setting (looked like
typo).  if ROOTSYS is defined then can we assume that paths are also set
for root?
Merge branch 'master' of github.com:ManyUniverseAna/RooMUHistos
add doxyfile
changes to environment to make RooMu easier to use

- fix env_set bugs so it really works from wherever you call from
- add a bin area to PATH
- create a roomu-config script to provide the caller with information on
  how to build against RooMu (e.g. roomu-config --libs)
- Teach makefiles in macros to use roomu-config
- put $ROOMU_SYS in the include path, rather than PlotUtils.  This is to
  force/allow code to write PlotUtils in the include statements.
   - all changes to cxx and h files are to implement this change
- remove makefile generator.  it isn't too flexible and the roomu-config
  script takes much of the pain out of creating makefiles.