Minor fixes and suggestions

[S1man]

There are a couple things that are standing out that I noticed that could be bugs or small oversights:

1) Flak Guns air firepower is not affected by conventional gun optimization.
2) 5000 kg bombload firepower oddly standing out of progression in firepower: probably should be 800 instead of 600, right now it is the only case when doubling the load (to 10k) improves firepower more than twice (to 1500).
3) OHQ colors over counters are not displayed in HIStory review, please add them.
4) Plane cost projections in Blueprints tab are inaccurate on planets with high Hazard Level.
5) Extra entrenchment from Entrench posture is lost after 1 turn if you remove the posture, it would be really cool if extra entrenchment would remain until troops move.
6) MG ammo consumption should probably be scaled down to about 3/4 of what it is right now (expecially important for Quad MGs).
7) Oil Depots should probably be doubled in size to match progression of Power Banks given the volumes in which oil is consumed.
8) Reduce Forced March PP cost to 4, its a very situational stratagem and Heart in generally is the weakest profile so both could use some help.