Don't give player translucency when looking down with the orbital camera

See merge request !659

Accurate papersprite projection

See merge request STJr/SRB2!657

Software FOV

See merge request STJr/SRB2!662

Don't clip player MD2 when looking straight down with the orbital camera

See merge request !658

In theory, should be a performance improvement. In practice idk

I heard properpaper had some weird crashes? I couldn't reproduce
them no matter how hard I tried, but I added some bounds checking
to this version too just in case. Gotta get other people's help
to try to reproduce those.

Update copyright statements for changed names

See merge request STJr/SRB2!644

Apply skin's highresscale to continue screen

See merge request !645

More OpenGL fixes plus masked PNG conversion

See merge request !619

Fix mouse being grabbed even when not used

See merge request !639

The other way around this time.

This reverts commit 6c85c4e1.

Fix usage of V_GetColor

See merge request !638

Use GCC 8.1 for AppVeyor 64-bit builds

See merge request !624

Add clipboard functionality to the Connect via IP textbox.

See merge request !597

I was using V_GetColor in a lot of places I shouldn't have, making the game look wrong with a non-default colour profile.
Though, I left R_RainbowColormap alone.

Fix major issue

See merge request !625

Remove Direct Draw from AppVeyor config

See merge request !622

Do not save netgame-synced console variables

See merge request !623

Let the mouse move freely when a menu is open or game is paused

See merge request !617

This is a bad thing to do, because if you join a server,
your game will save the host's settings.

This reverts commit 17636ccc.