Saving work made so far improving and optimizing addons menu code, also adding some macros and comments for readability

# Conflicts:
#	src/d_main.c
#	src/dehacked.c
#	src/m_menu.c
#	src/m_menu.h

Update game-emu-music lib to 0.6.2

See merge request !444

SDL:Update XPM icon

See merge request !441

Tails bot dead forever fix

See merge request STJr/SRB2!461

Show line number on error, also hide under devmode

See merge request STJr/SRB2!458

GCC8: Disable multi statement macros errors.

See merge request !459

Fix rendering gaps on polys with upper/lower textures

See merge request !453

Fix skin overflow error

See merge request !455

Emblem and unlockable softcoding

See merge request STJr/SRB2Internal!210

In-map emblem coordinates are now set via emblem mapthings (thing type 322) instead of X/Y/Z fields in SOC

Emblem and unlockable SOFTcoding! Emblems and unlockables are no longer predefined in the code and instead loaded from IWAD

I really hate that PlayerMenu status hack, but that's really the only
way I could think off to show the entires for Tails, Knuckles and the
Sonic&Tails pair.

Sal authored 6 years ago and SteelT committed 6 years ago

Co-authoered-by: Steel Titanium <(steeltitanium1@gmail.com>

Disable the APNG code if the version of libpng is greater than 1.4.

See merge request !457

Since supposedly the current code *can't* work with newer versions of libpng that have the apng patch, it won't compile if that's what people have.
It seems like some distros are adding the apng patch to libpng and that'll make things annoying to compile for people.
I think it goes without saying, but if there's ever a fix to make newer libpng versions work with the APNG code then this can be reverted.

Post-2.1.23 public next merge (20190101)

Closes #46, #47, #45, #43, and #37

See merge request STJr/SRB2Internal!209

(I believe Sal wanted us to do this anyway, so...)