Attached patch removes several roles, admittedly with no clear policy. Mainly I've considered if there's already lower tech level unit that does the same thing as well as the unit in question, and if the role is too far from unit's main function (shouldn't give strong attacker's as "passing" defenders)
civ2civ3/sandbox part of the StartUnits clean up requested by ihnatus in https://www.hostedredmine.com/issues/870579
Handling these two rulesets together as they are likely to get exactly the same changes.
The original ticket is (currently) targeted to S3_0, but maybe we should not touch rulesets in that branch with this? (Targeting to S3_1)