Additional research slot IS needed to play the game and use all units

Hello.

As we discussed in a CoW PL Community discord what improvements can be done to the game, we came to the conclusion, that in the current game state it's impossible to play more than standard meta type units. Let me explain.

In the current game state meta is still pretty similar to the one that was proficient in 1.0, which is artillery + planes + tanks. There are some changes, like replacing tanks with motorized infantry or making med/heavy tanks viable, but overall it keeps being the same. As we discussed why is it that the same units prevail, we came to the conclusion, that it's because of few factors:

- Long research time for higher tier planes, which are required to play which blocks at least 2 research slots for a long time, since to play you need at least fighters + some kind of bombers

- Long research time for atom, which makes it almost not worth it, since it blocks your research slots for a long time, and puts you behind, which means that you will probably lose before you will be able to get some nuclear power, unless you were already overpowering your enemies

- Maps duration too short to get all research to even medium level, while specialization in few kinds of units always prevails, which means you need to specialize if you want to beat your specializing oponent.

- No enough resources to research all the time since the beginning of the map, which makes research slots not used all the time for first few days.

Those, and few other reasons are the main points, that made us come to the conclusion, that at least third research slot around 10th day of game is needed to unlock full 1.5 fun, especially on 100p world at war map. Furthermore we think that even fourth research slot should be unlocked at some point in lategame.