This change makes ".xkcd" module more robust:

- don't allow negative numbers which accesses a comic number lower than 0
- don't allow the 0th comic when randomly checked
- allow also a "+" and "#" as a sign
- don't show an error when accessing #404
- don't show an error when no search.google_search() returned None
Make time units case insensitive
this fixes #609
[search] skip duckduckgo adds and show first real link
this fixes #599
[github] Properly quote issue search query

This allows for more than keyword to be used.
Merge pull request #613 from creesch/patch-1

[github] Properly quote issue search query
Merge pull request #611 from warddr/issue559-duck

[search] skip duckduckgo adds and show first real link
Merge pull request #610 from warddr/issue609-RemindToLower

Make time units case insensitive
Merge pull request #587 from xZise/patch-1

More robust number check
[find_updates] Add a module to check for updates
[version] Remove previous update checking
[NEWS] Update for 4.5.0
Release version 4.5.0
[__init__] Add -git to version number
[CONTRIBUTING] Touch up issue submission guidelines

Because nobody ever seems to read them before submitting issues. I'm
guessing it's at least partially because they're scary plain text, so
maybe making them an ordered list of short instructions in rendered
Markdown will help.
[find_updates] Fix unbound variable error on startup
[bugzilla, github, reddit, youtube] Remove handlers on shutdown

This solves #615. When reloading these modules, a new compiled regex
object was created and inserted into the url handler set. Because it was
a new object, it didn't replace the old one (even though the pattern was
the same). This meant that every time the module was reloaded, another
version of the function was added, meaning the output would be produced
an additional time.
Merge branch 'master' of https://github.com/embolalia/willie