Fix issue #191 : More flexible input of current and stop position in seek dialog.
When using media time format the hours and minutes fields are optional and all fields are floating point can be positive or negative.
Using the prefix LL is treated as reference time.
e.g. 
1:2:3 is 1 hour, 2 minutes, 3 seconds (as before)
2:3.5 is 2 minutes, 3.5 seconds
10.1 is 10.1 seconds
1:0:-0.001 is one hour minus 0.001 seconds
0.01:0:0 is 0.01 hours
LL12000000 is 12 million reference units or 1.2 seconds

The LL prefix is allowed but has no effect if using other time formats such as frame, sample. These are all in REFERENCE_TIME units anyway.


git-svn-id: http://graph-studio-next.googlecode.com/svn/trunk@275 c2f33eb2-41b2-391d-4cb4-d9d0608729ba