Ignore HTOA by default and add -H, --htoa switch.

Morituri will currently blindly rip ANY pregap marked as SILENCE in the TOC of a CD. Most of the time this isn't actually HTOA but a few frames of nothingness. In these cases there is little reason to clutter logs and filesystems with an extra file containing a few dozen frames of silence. This patch disables ripping the HTOA by default and adds the -H, --htoa switch to force ripping the HTOA as before. Changes should be minimal.

Note that this means CDs with track 1 pregaps will now pass the what.cd logchecker.

The .cue file will mark the first track with a PREGAP as it should.