Add option to use a 'current' character

Substracts one character from 'complete' and adds the 'current' between 'complete' and 'incomplete'. Defaults to the 'complete' character.
Fix aesthetic bug

Fixes bug where, if complete, current or incomplete chars had different number of characters, it would:

a) Create an undesired 'shrinking' animation
b) Raise an exception when getting to 100%