* proc: make some type casts less counterintuitive
The interaction of type casts with load configuration is sometimes
counterintuitive. This commit changes the way it is performed so that
when converting slices to strings and vice versa the maximum size
corresponding to the target type is used (i.e. MaxStringLen when
converting slices to strings and MaxArrayValues when converting slices
to strings).
This doesn't fully solve the problem (conversions to []rune are
problematic and multiple chained type casts will still be confusing)
but removes the problem for the majority of practical uses.
Fixes#3595, #3539
57dad9342a