Revise granule generator

[GoogleCodeExporter]

Granule generator seems to be the most complex code in the C source of ADDA, 
which is definitely not sufficiently commented. The bugs that were discovered 
in it are fixed, and additional testing was performed. However, there is 
clearly a need to look upon the code once again and add many comments to 
explain how it works.

Original issue reported on code.google.com by yurkin on 4 Sep 2010 at 2:41

• Blocked on: #108, #109

[GoogleCodeExporter]

Original comment by yurkin on 3 Aug 2014 at 4:58

• Added labels: Component-Logic, Priority-Low
• Removed labels: Priority-Medium
• Now blocked on: #108, #109

[myurkin]

Should also be made compatible with rectangular dipoles - see #245