* Pixma backend (pixma.c/pixma_common.c/pixma_io_sanei.c/pixma_bjnp.c)
bjnp tcp connection is now de-activated after initialization and
re-activated at start of scanning. If we do not do this, the scanner
closes its side of the connection after 30 secods of inactivity.
Added a maximum to the retry of slect calls when signals are
received
Added blocksize detection for tcp read_bulk call
* use own error codes e.g. PIXMA_EPROTO instead of EPROTO
* add MP530, MP800R and MP360
* add grayscale mode for MP700 and MP730
* add work-around for lock-up ("hang") problem of MP760 and MP780
* fix line correction (color alignment) for MP760
Nicolas Martin