Insert timeBeginPeriod in Windows implementation

[Expo88]

Based on this article: http://randomascii.wordpress.com/2013/04/02/sleep-variation-investigated/ I think that Tracker performance could be corrupted from a low timer frequency. I have inserted the timeBeginPeriod(1) call in the main before the GUI parsing of setting file (it is only to rapidly find it, there isn't any choices behind) and the performance increase a lot. Maybe it could be based only on my problems, but could be useful to make other test.