Ceramics
initial commit.
rng is done,
mapgen functions not yet
Recipies

Arrows, rock tools, quern, fire drill
Can't build walls, well, fireplace, pebble, rock sock, pot
Tweak
Tweak2
Vehicles don't collide flat terrain even when it's bashable.

The flat terrain check is based on the movecost being 2 (e.g. floor).
Tweak3
fix
Fix display bugs in editmap:

Check furniture/terrain count module available width, previous code used the wrong value for this modulo check.

Correct width of furniture/terrain list calculation, note that the loop starts at x = 3 and goes to x = pickw, so there are pickw - 3 items per line,
this means the number of lines must be calculated based on pickw - 3.

Removes num_terrain_types and num_furniture_types, instead use terlist.size() / furnlist.size() directly, what's the point of storing those numbers separately when the vector already contains them?
Shard description and major formatting

Hope you don't mind restyling
rng error fixed. list needs Jsonizing
Add hint for tagging PRs with link to fixed issue

to allow automatically closing the PR upon merging.
Also fixes a spelling mistake.

Code style: replace tab with spaces as it is demanded by the code style.
Replaced tabs with spaces

My mistake plus couple not mine
Merge pull request #8955 from jcd000/tree-spawn-chances-fix

Tree spawn chances fix
Merge pull request #8951 from BevapDin/fix-vehicle-dragging

Fix vehicle dragging
Mainline merge

So had to undo some formatting for now
Merge pull request #8953 from BevapDin/enhance-documentation

Add hint for tagging PRs with link to fixed issue to CONTRIBUTING.md
Merge pull request #8950 from Snaaty/fix-coldblood-display

Fix for display bug in "Heat Dependent"
Fix
No ceramic hammer