Optionally add a separate calculate fn for each pointer label

Adds settings options `calculateFrom` and `calculateTo`. Both
settings expect functions. The function will be passed the current
value of the respective pointer. The return value of the function
is displayed in the pointer's label.
Adds `calculateLeftValue` setting

This setting expects a function that will be passed the values
of both the from and to pointers. The return value of the function
will be displayed to the left of the from pointer handle.
Rename calculate(From/To) to translate(From/To)
Left and middle values get class mini-label when small

If the size of "i.l" or "i.v" go below 13% then the class
mini-label will be applied.
Include predimension on to-label when gluing labels
Changed mini-label break point to 18 percent
Update slider handles in proper order

This will make it so one slider handle won't prevent another from
updating.