I am a native speaker. I have corrected all the mistakes I've found.

Update Spanish language

Caves check for biome nodes, only excavate stone under water level
Unease caves noises, use MT0.3 parameters
Blobgen after cavegen
Biomegen: remove 'is replaceable content' bool

Add -Wall to Debug modes for all compilers and -Wabi for non-MSVC
Use /Ox for MSVC Release mode (potentially higher optimization than /O2)

This reverts commit 7b17b905.

This reverts commit 839c4a99.

-O1 results in executables that are completely useless for actuall debugging

Clean up nearby code a bit

As a small side effect, it is now possible to add a background texture
to the chat console by simply providing background_chat.jpg, it is no
longer necessary to also add "console_color =" to minetest.conf.

Change must_reflow to a deque
Add overload for MapBlock::raiseModified that takes a const char*. This is a speed improvement.
Comment out unused variable
Optimisations to block offset calculations

OpenGL_vertex:
* bufferize a duplicate calcul
* Factorize vertexes

Add optional core.pos_to_string decimal place rounding
Move core.string_to_pos to builtin/common/misc_helpers.lua for consistency

Also add a Lua API and chatcommand for this

This reverts commit 148fffb0.

OpenGL_vertex:
* bufferize a duplicate calcul
* Factorize vertexes