Add new key actions for zooming: PgUp / PgDn

As all hotkeys, this can be reconfigured through the hotkey dialog or by
manually editing the settings file.

Closes #2265 (Zoom In/Out shortcut).
Fixes #2260
* Fix AI trying to enlarge settlement with tents
* Fix AI trying to build trees outside the settlement range
Reserve trees that are still outside the settlement, so they are not
built over at a later stage
Rename resource dagger to sword.
Try to fix #2264 with Thomas help.
Add open method to windows

This becomes the opposite of close, similar to how show and hide work
together. show is no longer part of the window managers public API, it's
now open. This gives us the possibility to run code the first time a
window is shown.

After an idea of @myrdd.
Make pause & resume work correctly

Pause the game when the pause menu is open.

Fixes #2211
Translated using Weblate (Korean)

Currently translated at 26.6% (222 of 834 strings)
Translated using Weblate (Korean)

Currently translated at 77.4% (148 of 191 strings)
Translated using Weblate (Korean)

Currently translated at 100.0% (27 of 27 strings)
Translated using Weblate (Bulgarian)

Currently translated at 100.0% (191 of 191 strings)
Translated using Weblate (Catalan)

Currently translated at 79.7% (665 of 834 strings)
Rename armory and add graphics for weaponsmith building.
Translated using Weblate (Bulgarian)

Currently translated at 100.0% (191 of 191 strings)
Change build menus to find the weaponsmith.
Translated using Weblate (Bulgarian)

Currently translated at 39.8% (332 of 834 strings)
Delete duplicate images from weaponsmith idle folder.
Merge branch 'master' of https://github.com/unknown-horizons/unknown-horizons
Translated using Weblate (Bulgarian)

Currently translated at 41.4% (346 of 834 strings)
Add resource icon for sword resource.