Copy filter now converts from imperial to metric

 * Convert ft to m, inches to either mm or cm (depending on the size), and lin. to mm.
 * Converted measurements less than 5 units given with 1 decimal accuracy, otherwise 0.
 * Anything less than 4 inches (about 100mm) it converts to mm, while anything 4 inches and up it converts to cm.
* Ranges are handled gracefully (e.g. 2-6 in. converts both the 2 and the 6).
* In a range, formatting decisions are made based on first measurement but apply to both (e.g. inches to mm or cm; value with one or no decimals).