doc: fix documentation of setindex! [closes #2993].
Repair rand{T<:Integer}(r::Range1{T}) for signed types. Closes #3004.
Merge pull request #3008 from GunnarFarneback/rand_from_range

Repair rand{T<:Integer}(r::Range1{T}) for signed types. Closes #3004.
fix bug in finalizing weak keys and values in dictionaries
fix ambiguity in scale!. fixes #3006