added RALint check for missing sequence definitions

closes #2283
add missing d2k sequences

- removed some hidden ra fallbacks
- added waypoint/spawn for editor
update the d2k missing content files readme text
A Drop Zone map for C&C
tanks get increased spread, 3 -> 6

Tanks get chewed up pretty good by bazookas, and dont do much damage to infantry. This will help a bit to hurt infantry that are clumped up in the same cell.
Merge pull request #3093 from Mailaender/ralint-sequences

Added RALint check for missing sequence definitions and fixed them in d2k mod
Merge pull request #3103 from ScottNZ/missions

Add `Required` slot checking in lobby logic. Set up needed player slots as Required for missions
increase turret strenght vs. vehicles a bit

gun tower should dispatch light vehicles as fast as the heavy.
turret got little buff vs. tanks since it's much weaker than gun.
tanks get buff vs. light armor

Tanks are a little under-performing vs vehicles. They should be able to dish out damage closer to as fast as light vehicles do to each other.
added stealth trike to show up in crates
Merge pull request #3101 from psydev/patch-1

d2k-tanks get increased spread, 3 -> 6
QuadRockets and Bazooka are no longer "high"

Quad spam can be potentially very powerful. Gameplay-wise, one should be able to avoid their powerful missiles by hiding behind a building or a wall.
It doesn't necessarily make much sense that a vehicle low to the ground should be able to shoot over things perfectly. Same for infantry. 
The advantage of shooting high should be reserved for units like artillery, so you can put them behind walls or other obstacles. Makes gameplay more interesting and dynamic. 

TowerRockets will stay high.
updated map, dead in motion (redux)
Merge pull request #3108 from psydev/d2k-balance

D2K--QuadRockets and Bazooka are no longer "high"
Merge pull request #3109 from psydev/cncmap

updated map, dead in motion (redux)
Merge pull request #3100 from dan9550/created-maps

A Drop Zone map for C&C
Merge pull request #3110 from ScottNZ/renderer

Fixes #3104
Make MRJ jam radar
Add missile jamming to MRJ
Add RenderJammerCircle