#1 Installation with pip and more bugs

This is massive refactoring. Needs testing.

Breaking changes:

• Moved scripts to cgi-bin/ and changed links accordingly, some action is required to keep old links working.
  Rationale: wider server support.
• Old scripts won't run because of different command-line flags.

Rationale for antenna install: support running multiple Antenna instances on the same machine (e.g. for different languages).

Rebased my commits. Some unrelated changes:

• printPage function is back
• Add URLHelper.resolve() function to resolve relative URLs
• Add support for relative redirects in antenna refresh
• Force static pages generation if index.gmi does not exist (ingestfeeds-wrapper.sh)
• Avoid ZeroDivisionError when there are no feed entries (first run)

I could forget to apply some recent commits, so double-check that they are included.

• Split my commits, so they are easier to review
• Added unit tests

• Removed antenna install command
• Added unit tests for customFilters