Small hotfix for start game balance issues

Since adding shields to the items enemies can have at low tiers, it was a bit too difficult at start game.

The following changes have been made to fix this:

• The default layout has been changed. The Sidewinder was switched for a Bobcat with a utility slot

• The default MCV now has an EMP gun instead of a mine thrower

• The Shield Mk1 now negates 100 HP instead of 150

• The repair drone now has a cost value again!

• Some typos in scenarios were fixed