add command-line option to feed in image names

[rfinn]

• selecting from file menu is tedious, especially when in testing mode
• add two command line options to load r and ha image

halphamain.py 0 --r /full/path/to/rimage.fits --ha /full/path/to/haimage.fits

[rfinn]

• also figure out a better way to load catalogs!

[rfinn]

I have added several new flags to set at the command line.

python ~/github/halphagui/testing/halphamain.py --help
usage: halphamain.py [-h] [--table-path TABLEPATH] [--virgo]
                     [--pointing POINTING] [--nebula] [--laptop] [--testing]

Run gui for analyzing Halpha images

optional arguments:
  -h, --help            show this help message and exit
  --table-path TABLEPATH
                        path to github/Virgo/tables
  --virgo               set this if running on virgo data. The virgo filaments
                        catalog will be used as input.
  --pointing POINTING   Pointing number that you want to load. ONLY FOR VIRGO
                        DATA.
  --nebula              set this if running on open nebula virtual machine.
                        catalog paths will be set accordingly.
  --laptop              custom setting for running on Rose's laptop. catalog
                        paths will be set accordingly.
  --testing             set this if running on open nebula virtual machine