Modified example to use new LiSystem type.
Added ignore file.
Created proper type families for LtiSystem. Changed example to match.
Merge remote-tracking branch 'upstream/master'
add alternate isLTI function

ideally this adds the appropriate constraints on a,b,c,d
provided the other arguments have correctly annotated types.
But the functions involved are not good enough for that yet.
Merge https://github.com/dmcclean/DimMat
merge controlspace. Re-add instance Show LiSystem