Update manpage

[bjorgan]

Update manpage in docs/man/.

• [x] Basic manpage covering all tools and command line options.
• [x] Remove incorrect information in the manpage
• [x] Consider whether the remaining information is useful or not, reduce to bare minimum
• [x] Convert blogpost about flyby on http://la1k.no to markdown, update any changes since it was written
• [x] (automate the screenshotting?)
• [x] Reorganize README, no need to mention paths for TLEs and transponder database before the easy way to obtain these files
• [x] Dependencies in README

[bjorgan]

Fixed in 97d1c1be129acd0d1f270774eddf0ea507a9f318