Add: Website button to Game Options window for basesets.

This links to the optional "url" item in the baseset's [metadata] section.

Change: Move baseset missing/corrupted files label to list item. (#11455)

This allows any baseset error to be displayed in the drop down list so it is more easily visible, and avoids wasted space in the layout.

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

Non-const version of GetItem is not needed.

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

Fix: Truncated music-set song names cause warning log.

The music-set does not need to be selected for this to occur.

Resolved by using std::string instead of fixed buffer for song names,
which avoids manual string copying and removes the length limit.

Codechange: Use override specifer for overriding member declarations

This is a C++11 feature that allows the compiler to check that a virtual
member declaration overrides a base-class member with the same signature.

Also src/blitter/32bpp_anim_sse4.hpp +38 is no longer erroneously marked
as virtual despite being a template.

Fix: Don't complain if CAT music files are missing entirely

Just complain if an index into a CAT file that exists is invalid.

Change #6684: Cutting point overrides for music base sets

This improves bad looping of title screen song from Windows TTD, and fixes
a long silence at the end of "Can't get there from here" from Windows TTD.

Feature: Decoder for DOS version music

This is based on reverse-engineering the TTD DOS driver for General MIDI music.

Codechange: Pass a MusicSongInfo struct instead of bare filename to music drivers.

Preparation for later extending the info passed to music drivers.

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