Map modifier aliases to actual modifier names for easier lookup.

Reduces use of lots of switch statements.  Alias-to-modifier objects contain data for how to map the data back to the actual modifiers.  A couple of functions allow for setting and getting where we were previously going through a long switch/case statement to set and get each value.

@scottnc27603 @eric79 
Similarly as above, I think that:

    updatedUnit.validModifiers.push( alias );

reads a little nicer.