Codechange: Add const versions of GetItem/GetGroup, and sprinkle liberally.

Non-const version of GetItem is not needed.

Codechange: Remove create parameter from IniLoadFile::GetGroup.

GetGroup now only returns nullptr if the group does not exist.
Use GetOrCreateGroup to create a group.

This avoids creating groups while reading ini files.

Codechange: Pass ini file by reference and prefer automatic storage.

This avoids new/delete operations, and (not) checking for nullptr.

Codechange: automatic adding of _t to (u)int types, and WChar to char32_t

for i in `find src -type f|grep -v 3rdparty/fmt|grep -v 3rdparty/catch2|grep -v 3rdparty/opengl|grep -v stdafx.h`; do sed 's/uint16& /uint16 \&/g;s/int8\([ >*),;[]\)/int8_t\1/g;s/int16\([ >*),;[]\)/int16_t\1/g;s/int32\([ >*),;[]\)/int32_t\1/g;s/int64\([ >*),;[]\)/int64_t\1/g;s/ uint32(/ uint32_t(/g;s/_uint8_t/_uint8/;s/Uint8_t/Uint8/;s/ft_int64_t/ft_int64/g;s/uint64$/uint64_t/;s/WChar/char32_t/g;s/char32_t char32_t/char32_t WChar/' -i $i; done

Codechange: Split GetItem with GetOrCreateItem. (#10952)

`IniGroup::GetItem()` returns nullptr if the item does not exist, but does not if the create parameter is set to true. Resolve CodeQL warnings with `GetOrCreateItem()` which returns a reference to the item instead.

Codechange: use "[[maybe_unused]]" instead of a wide variety of other ways we had

While at it, replace OTTD_ASSERT with WITH_ASSERT, as this
is always set if assert() is valid. No matter if NDEBUG is set
or not.

Fix: ensure switching blitter happens in the main thread

This because video-drivers might need to make changes to their
context, which for most video-drivers has to be done in the same
thread as the window was created; main thread in our case.

Add: 32bpp SSE2 blitter palette animator (#6795)

Create a new blitter mode: 32bpp-sse2-anim, which is 32bpp-anim + this.
32bpp-sse2-anim is now used by default where 32bpp-anim would have been.
Also use this with the 32bpp-sse4-anim blitter.

See issue #6469.

(svn r27730) -Change: Split openttd.grf into openttd.grf and orig_extra.grf
openttd.grf is now always loaded and provides all extra graphics in case the (possibly outdated) baseset does not.
orig_extra.grf contains graphics specific to the original baseset only.

(svn r26522) -Add: A config-file-only setting to disable usage of 8bpp video modes.
-Remove: [win32] fullscreen_bpp setting, which is replaced by above setting.
-Change: Disable usage of 8bpp blitters and video modes by default. Many modern OS and hardware cause issues with those.

(svn r22419) -Change: Always use the DOS palette for drawing.
-Remove: the '-i' option for palette selection.

(svn r17238) -Codechange: Clean up CheckExternalFiles a bit and improve the error message it
outputs. This makes the function return faster in the common case when all
files are in order, by not doing another set of MD5 checks.

(svn r16269) -Codechange: use gcc's ability to check parameters sent to printf-like functions
-Fix: wrong number of parameters or wrong parameter types sent to printf-like functions at several places