Added a tool to find units

perl script
given a set of unit properties, the CIV4UnitInfos.xml is parsed for units
matching those properties.
fix assertion

Unit UNITCLASS_ADVANCED_POWER_ARMOR has defined collateral damage as 100 but no collateralDamageMaxUnits.
This game tries to assert the opposite.

I set the latter value to '10' for now, not sure what the best value would be there.
fix assertion: AI route calculation

I split up a bunch of nested function calls where the inner one returned a value that the
next function call wasn't expecting.
Added an additional check for the inner return value to prevent the assertion.
fix assertion: paratrooping count was 0
TODO update
fix assertion: AI civic eval

One of the civics contained negative values for the free unit modifiers inside its xml desc.
This seemed to have caused a flawed calculation for the AI players on that civic (gov_representation)
fix assertion: collateral dmg

Changed up two more unit descriptions in the XML because they where defined
<iCollateralDamageMaxUnits>10</iCollateralDamageMaxUnits>
as 0.
note about assertion

todo update about an assertion that occurred in a similar matter previously
it is concerned with an invalid value in array m_aiFreeCityCommerce[]
need to watch for assertions when those values are set, not read