refactored v1.3

Added a full Changelog.txt file, you can read it to see all changes made (including previous versions).

General Changes:

• Added the Heavy Repair Turret.
• The Heavy Repair Turret can be researched after picking up the Dedicated Synaptic Link Data Analysis artifact in Beta 7 (NASDA Central).
• The Collective will occasionally build Heavy Repair units starting from Beta 6 (Nuclear Plant).

Level Specific Changes:
Alpha 8 (LZ 2 Mission):

• Halved the rate at which NP heavy tanks are produced.

Alpha Final:

• Reduced the production speed of the three vehicle factories, halving the north-east one that produces only heavies.

Beta 4 (Commander Interception):

• Slightly reduced the rate at which lancer hovers are produced in the north-west base.
• Lancer VTOLs now attack more frequently, but only in groups of four.
• VTOL strikes can now be stopped by destroying the HQ in the north-east base, as instead of the north-west.

Beta 5 (Air Base Assault):

• Doubled the production time for all VTOL and vehicle factories.

Beta 7 (NASDA Central):

• Significantly increased the production time for the four vehicle factories.
• Diversified the outputs of the vehicle factories a bit.
• Tanks built from these factories now attack more frequently in smaller groups.
• Collective VTOL attacks now alternate between groups of Lancers, Thermite Bomb Bays, and HEAP Bomb Bays.
• Lancer VTOLs attack in groups of four, while bombers attack in groups of two.