Merge branch 'master' into gameplay/devserver

Conflicts:
	src/gamelogic/game/g_admin.c
Tweak unlock thresholds for dev game.
Merge branch 'gameplay/viech' into gameplay/devserver
Merge branch 'master' into gameplay/devserver
Merge branch 'gameplay/master' into gameplay/viech
Build detour & nettle only once (if needed).
Fix listing of items (un)locked.

Problem was of the form 'sprintf(buffer, "%s…", buffer, …)'.
Revert "Build detour & nettle only once (if needed)." – too soon for this.

This reverts commit 8559f173f1b8d80b5c09fb6122ba83ae7e70df75.
The cmake feature used in this commit was added in cmake 2.8.8.
Unfortunately, travis uses an older version.
Add support for icons for buildings & classes.
Draw unlocked classes, weapons, upgrades and buildables.

This may extend beyond its allocated area; no clipping is done.
Vertical rendering has not been tested.
Fix locale handling for input etc. on *nix.

Without this, some input, e.g. compose sequences, could be mangled.

I found that <compose> <apostrophe> <a> was causing ‘Ã¡’ to be input – this
just happens to be the result of conversion from Latin-1 to UTF-8 of ‘á’
when already represented as UTF-8.
Rework unlockables display: show those initially locked, grouped by threshold.

Also adjust sizes and use the background colour for disabled items.

Items are shown in groups, using the full width (or height) of the box and
with equal spacing between groups.

Aligning the icons with the threshold marks leaves much more scope for
overlap; and with commit 91751a3 merged, they do indeed overlap unless
shrunk – which would leave them too small.
Fail the fight task if the enemy is no longer reachable
Add a navmesh testing command
Tell the user when the navmesh name does not exist
Fix acid tube shell inner surface (culling).

This is the same problem as with human armour – could be seen through from
inside.
Don't do friendly weight damage.
Fix attribution of damage dealt by ET_FIRE entities spawned by the firebomb's submissiles.
Fix pulse rifle means of death.
Merge branch 'debian'