New melee spawn control extension

I have installed my modified melee spawn control SourceMod extension (l4d2_meleespawncontrol.ext.so) now on 17/19/20/21/22 too.
On 16/18 it was already installed a little longer.

Since there is a limit of 16 melee weapons the new extension will take care that at most 16 melee are available.
The extension will use the melee list specified in a campaign first, then fill this list with other official melee weapons until 16 is reached.

Currently the only campaign with many custom melee weapons is "Redemption II".
And therefore "electric_guitar" and "riotshield" is not available in "Redemption II" maps.

For all other maps, the complete list of official melee weapons plus the custom melee from the running campaign should be available.