multiplication regex: Experimental unfinished changes, towards reducing specialness of special case for multiplication by 1
multiplication regex: Streamline test at end of division loop; length-=11
multiplication regex: Getting closer to experimental goal, perhaps
multiplication regex: Alternative way of enumerating all prime factors of P

This results in a speed improvement.
multiplication regex: Make a comment more accurate in light of a recent change
multiplication regex: always divide down the smaller of \1 and \2 along with P; length+=9

This partially fixes handling of multiplication by 1, and should mean smaller special-case handling for when multiplication of 1 is fully fixed.
multiplication regex: Remove capturing of absolute value of \1 - \2; length-=36
multiplication regex: Fix comment regarding which prime power corresponds to \1 or \2

This should have been done in commit 9612dcd80cddeb58e6b18cfaa4ba6c8013635b71
multiplication regex: Remove space from "\ 9" where it's not needed for alignment

This should have been done in commit 45f2531a84e60bd80886d04604183f020a9aa4ac
multiplication regex: Fix comment regarding which prime power corresponds to \1 or \2

Commit b565714599f892301f2d614fabc971b4d2204803 got it wrong.
multiplication regex: Restore full functionality; length+=12

The regex is now much faster than it was before these (formerly experimental) changes, and is now 655 characters in length, whereas it was 667 without these changes.
Merge branch 'experimental'; length-=12

Conflicts:
	regex for matching multiplication.txt