Update test-mutate.r
make colwise deal correctly with replicated names
add test cases for colwise
rbind.fill checks for factor-on-character. Fixes #128
update NEWS
Merge branches 'update-rd', 'fix/137-id-column-as-factor-3', 'fix/tjmahr', 'fix/vitoshka' and 'fix/128-match-factor'

Conflicts:
	NEWS