Graphics update for progressbar
Background image for progress bar. Fixes #1650

And somewhat minor refactoring. Now exposes attributes to xml.
Changed behavior which can be extended/generalized later:
* Fixed background size of currently 100px; has to match max amount
* Fixed progress tile of currently 1px
* No special left/right framing tiles
Use background attribute for ProgressBar
Call tile-laying even if no background exists

Turns out it is not important to draw the background behind other stuff.
int() for progressbar amount

Boat builder for instance was passing floats here.
"name" instead of 'name' for xml file

In the name of coherence.
Boat builder layout update

The funny max_size there restricts the bar height and thus scales all
icons, which is easier interface-wise than implementing own "height"
attributes and also more flexible even if weird-looking at first.
Update installer script
server.py writes wrong pid in pidfile

it's chanserv fault!
add simple bash script to setup and run a uh master server
fix crontab sample
server_check.sh: replace cron with quiet. makes more sense
Support setting active_tab for TabWidget

Should make it easy to work on #1941 in the sense of keeping the
current overview tab, but making inventory the default one.
Preselect inventory tab for warehouse/storage tent. Fixes #1941
Clean up active_tab implementation for SelectableComponent (#1941)

Now specifies the desired tab's name instead of 0-based index. Sadly,
this needs a bit more magic to work because the tab index can only be
determined after checking which tabs would currently be displayed.
Add hint about where our new dev MP server lives
Merge pull request #2007 from unknown-horizons/progressbar

Add background feature to progress bar and relayout it

This is a first iteration but should still work as-is.
In particular it'd be nice to have a horizontal resize feature instead
of hardcoding the exactly 100 tiles as widget size.
Bar height can be worked around using a max_size height component while
not restricting width.
Fix progress bars staying at initial progress sometimes

In particular, when directly contained in a widget without auto-resize.
Scale progress bar width with max_size parameter
Prevent infinite recursion in pychan

No available max_size does not go well with relying on a max_size for
defining background image size.