Variable stretching ideas

[cswhite2000]

Similar to https://github.com/PGMDev/PGM/issues/1001

This is an issue for types of variables that could be implemented to allow map makers to modify certain internal values, such as score, or blitz lives.

Keep in mind, that not all of these must be viable to implement, or make sense to implement. It's just a list of anything that could maybe be looked at, some may become impractical or nonviable upon closer inspection or when trying to look at details of implementation.

The ideas/brainstorming for future variable types:

• [x] Blitz lives - #1214
• [x] Score variables - #1220
• [x] Max build height variable
• [ ] Objective completion variables - Possibly read only
• [ ] Match time variables - readonly
• [x] Time Limit variables
• [ ] player state variables: ie health, hunger, xp etc: - some readonly
• [ ] stats variables: ie kills, deaths, killstreaks - readonly
• [ ] Player count variable - readonly
• [ ] Class variables - how many players have a class? - readonly

[Pablete1234]

Player count variable - readonly Class variables - how many players have a class? - readonly

Note for these ones, they can be computed in xml atm like so (given any filter to apply to players before counting):

<action scope="match">
  <set variable="archer" value="0"/>
  <switch-scope inner="player" filter="is-archer">
    <set variable="archer" value="archer+1"/>
  </switch-scope>
</action>