autocomplete handler for Impacts

[rsek]

i think the "some structure but you can go off-road if you really want" nature of autocomplete could handle these pretty well. it'd also allow us to include checks for, say, specific impacts that prevent condition meter increases or other mechanical effects, without too much worrying about whether someone misspelled the impact name or used the wrong case or something,

[rsek]

resolved in XenotropicDev/TheOracle2#33