option --filename-parse to get date in filename

I finally made it since I really wanted to organize video named with date pattern

It's far from perfect and has many flaws depending of the pattern I think but for now it work like that:

--filename-parse take multiple flags :
	L for little median (DDMMYYYY)
	M for middle median (MMDDYYYY)
	B for big median (YYYYMMDD)
	T for time (HHMMSS)
	A to ask when multiple match are found)
	
if you add L and M there a risk of wrong detection (since 04062012 can be 4th june or 6th April) so I added the 'A' flag which will ask user anytime multiples matchs are found (but don't detect multiple match of the same median in the same filename (like IMG_04052012_10122014.jpg) even if that's hardy probable.

T flag is not really useful for now (except if you use time in sorting option)