New drivers: voltronic_ser/voltronic_usb

Reference: http://article.gmane.org/gmane.comp.monitoring.nut.devel/6418
Add voltronic_usb driver to USB info extractor tool
voltronic_usb: switch to new is_usb_device_supported() syntax
Ignore voltronic_* generated documentation
Correct manpage references
Add comment so that autogen rules have the right comment
Add USBDevice_t structure
Improve docs layout
Correct typos & add software reference in HCL
Imrove shutdown sequence + versioning

Split shutdown and stopping of pending shutdowns so that if there's no shutdown pending and the UPS doesn't accept a shutdown.stop in this situation (i.e. it replies '(NAK') the
shutdown procedure doesn't get halted.
Increase version number of drivers.
Correct typos @shutdown.{return,stayoff}
Fix shutdown.return + versioning

Fix shutdown.return when ondelay = 0 -> split between offdelay < 60 and offdelay > 60.
Increase driver versions.
Fix warning flag + versioning

Some UPSes seem to reply with a \0 just before the end of the warning flag (obtained with QWS), as a consequence of that, the string in C is 1 char shorter than expected (the \r
is not within the string). -> Fix voltronic_warning function.
Increase driver versions.
Add devices to HCL
Add unknown/unused and commented capability entries

Might be useful for future versions.
Get rid of 'god.knows' variables
voltronic* documentation updates

 - Add to man page index
 - Reword a few sections
 - Fix typos
 - Comment out USB section in voltronic_ser.txt

Long-term, we should probably figure out a better way to maintain two parallel
driver pages like this. The blazer man page is the same for both, with
.so links for the man pages, but then you have USB info in a serial driver
page. For now, voltronic_usb.txt is just a copy of voltronic_ser.txt with a
few _ser-to-_usb replacements.
Merge branch 'voltronic-driver'

Adds voltronic_ser and voltronic_usb drivers.