docs updated
    modified:   notes.txt
    new file:   roadmap.txt
documented issue 21 and 28
    new file:   eppy/issue21.txt
    new file:   eppy/issue28.txt
made the following updates:
- added loopdiagrams.py in useful_scripts
- documented loopdiagrams.py
- fixed issue21
- added pyparsing to requirements.txt
    modified:   eppy/useful_scripts/loopdiagram.py
documented the changes in docs/source/changes.rst
still debugging for issue 28
see eppy/scripts_totest/issue28_play.py for
how to display the working of makeairloop
    modified:   eppy/scripts_totest/issue28_play.py
working on the incremental print of makeplantloop
plantloop steps & condenserloop steps done
fixed a pytest
    modified:   tests/test_hvacbuilder.py
cleaned up some files in eppy/scripts_totest
airloop replacebranch works now
updated notes
started a developer documentation using Sphinx
documentation update