#83 Disable bitstream padding

[Elio Blanca]

As an answer to the question

https://sourceforge.net/p/lame/mailman/message/35767332/

I created this patch some time ago. Now I fixed it to be mergeable with current trunk.
This basically re-enables the ability to disable padding during encoding (using command line option '-d'), this possibility was disabled many years ago. Still the default behaviour is adaptive padding.