rbind.fill checks for factor-on-character. Fixes #128
update NEWS
output_template treats dims orthogonal to type
extract method 'allocate_column'
rbind.fill accumulates data in closures
Compute attrs before alloc; specialize mutators

This acheives linear performance for rbind.fill on arrays, chars, lists.

Factors and POSIXt values will still be quadratic.
rbind.fill multiway arrays
rbind.fill linear tests; linear factors
Handle POSIXct in linear time
Format and update NEWS
rbind.fill respects matrix column dimnames
Always delay setting class attribute
Delete unused function
Adjust comments
Clean up test code
Organization suggestions
Check for data frame columns
strip dimnames for 1d arrays
Merge remote-tracking branch 'crowding/fastrbind' into develop

Conflicts:
	NEWS