Typed task editor
@rinus, @steenvoo, I made a fresh start and made an editor for simple expressions. For the
== the two argument expressions have to be of the same type. If not, the editor does not produce a value and an error icon is shown. The error message should be in the tooltip, but see #296 (closed). It is visually not very nice, but this can be improved later.
Next step is to deal with underspecified types, e.g. in
enterInformation >>| enterInformation.