`triminf` is invalid and untested

[mpf]

The function triminf is invalid — there is no find method in Julia:

ActiveSetPursuit.jl/src/helpers.jl

Lines 211 to 213 in b602cef

	tlistbl = find( state[active] .== -1 & bl[active] .< -bigbnd )
	tlistbu = find( state[active] .== +1 & bu[active] .> +bigbnd )
	tlist = [tlistbl; tlistbu]

Fix this function and create unit test.