Add/remove formats to operations

[gcurtis]

Starting and ending formats should do the following:

• When the last component within the operation is a format boundary, the new format should be added to the existing format boundary.
• When the last component isn't a format boundary, a format boundary should be created and have the new format added to it.
• When a preexisting format with the same name exists within a format boundary, it should be updated with the new value.