Fix 3 warnings reported by GCC 8.1 of the following type
```src/client/gameui.cpp:191:43: warning: « void* memset(void*, int, size_t) » effacement d'un objet du type non trivial « struct GameUI::Flags »; use assignment or value-initialization instead [-Wclass-memaccess]
memset(&m_flags, 0, sizeof(GameUI::Flags));
```
```
src/translation.cpp:43:16: warning: interception du type polymorphique « class std::out_of_range » par valeur [-Wcatch-value=]
} catch (std::out_of_range) {
```·
Because vein ore uses 3D noise (all the other ores use 2D noise) the
perlinmap Y size can be different in different mapchunks when close
to the ore Y limits.
Previously this caused bugs in the vein structure because changes in
perlinmap Y size did not recreate the noise objects.
Delete and recreate the noise objects with the new Y size if Y size
has changed.
Previously, the centering caused by the 'place center x/z' flags did
not take rotation into account. So schematics with unequal X and Z
dimensions were incorrectly placed. The bug was hidden for schematics
equal in X and Z dimensions.
Avoid crash in some situations when player is inside a node, causing
'above' to equal 'under'.
In this situation return 'under' which is the node position very close
to the face position that would normally be returned.
Add a new point to encourage discussion before coding. Move the 'ask
before significant coding' suggestion into this.
Edit and extend commit message guidelines. Refer to core dev commit
messages as good examples.
Remove 'short' and 'briefly' from the description guideline to try to
improve description quality.
Larger text for '### A pull-request is considered ..'.
Add a second roadmap link to celeron55's blog roadmap which is the 1st
part of the forum roadmap.
Add full stops to lists.
Consistent text size for '## Donations'.
* g_extrusion_mesh_cache new() and grab() to be managed in constuctor only (#7235 partial)
This global was getting grab()-ed by each call to getItemMesh, incrementing its reference count. What was to be the final drop() in the destructor ended up with > 0 reference count, so memory not freed by Irrlicht.
Previously, caverns confused tunnel generation causing biome top and filler
nodes to appear in caverns.
Split 'generateCaves()' into 2 functions to separate tunnel and large
randomwalk cave generation.
In each mapgen re-order cave generation to generate tunnels before caverns.
Split some long lines.
Edit comments.
Remove unnecessary comments and unnecessary commented-out code.
Use std::fmax/fmin instead of MYMAX/MYMIN.
Remove scope-limiting braces.
Consistently define literals as floats, except in noise parameters.
Cleanup literals in noise parameters.
Remove unnecessary 'near_cavern' line.
Reduce max spawn y to be consistent with other mapgens.
Caverns first appeared in mgvalleys and were later added to other
mapgens as shared code. Now this shared code can replace mgvalley's
internal cavern code.
Also use shared tunnel code instead of internal code.
Changes to mapgen that will affect existing worlds (mgvalleys is not
stable):
Single lava and water sources not added in tunnels.
Previous caverns are unchanged but an equal number of new ones are
added at a distance from the previous.
From y = -256 to 192 nodes below, where the caverns taper at their
upper limit, they will have a slightly different shape as the taper
is now linear.
