Issue2, issue18, issue22, issue21

[bjorgan]

Should probably deal with https://github.com/la1k/flyby/pull/23 first, as I've merged that branch into this one.

Things kind of clustered together, and it made sense to do more than introducing getopt-parsing only.

Major changes:

• Command line parsing using getopt_long in flyby_main.c (solving issue #2)
• Split main() and directly related functions into flyby_main.c.
• Deglobalized rotctld/rigctld variables, assembled in a rigctl/rotctl interface in flyby_hamlib.c/.h. (solving issue #18).
• Split ReadDataFiles in one function for each property (QTH, TLE database, transponder database)
• Assembled and documented UI functions in flyby_ui.h.
• Separated curses UI functions from the rest by renaming to flyby_ui.c.

Issue #22 is probably also solved, don't think it makes much sense to split flyby.c more.

Issue #21 is made redundant, since most settings have now been made part of various structs:

• rotctld struct contains horizon and once_per_second variables
• tle_db struct contains tle filename
• transponder_db struct contains db filename and whether db is loaded