Fix & improve objectplace

Closes #232

See merge request STJr/SRB2!1139

Avoid CV_FindNetVar returning a normal cvar (closes #251)

Closes #251

See merge request !1137

Can we just do this please? Thanks.

See merge request !1142

Remove BT_USE and PF_USEDOWN warning

See merge request STJr/SRB2!1138

PNG conversion refactoring

See merge request !675

Optimize PNG conversion

See merge request !1143

- movement speeds are scaled with player scale
- spawned objects are scaled with player scale
- command accepts argument for thing num to set

someone entertained the idea of maybe removing it, so might as well put this merge request up to see if people want it

Update credits

See merge request !1136

New STJR Intro and related changes (resolves #202)

Closes #202

See merge request !1132

(cherry picked from commit 3437b0690a3f4278e3ecc657102a126a3e2f3d13)

(cherry picked from commit 0d57ba1d02c5bde2ab22a71d21a95849b21e9539)

SteelT authored 5 years ago and James R. committed 4 years ago

(cherry picked from commit cb9004e4cfa94251ab0d31f19fee187fc4e9abcc)

(cherry picked from commit 7a05a8acf73ac0f012135339447c9a935e3b7939)

Make the scene time be 5 seconds long max

Use the standard fade which is much shorter in length.