pixma: add model by description

Gives the possibility to add a device according to the information added in the configuration file
Below is the form of the description and an example:

######## pixma.conf ##########
# TYPE : MP150 OR ICLASS
#
# device MP150 NAME MODEL PID DPI CAPACITE
device MP150 "Canon PIXMA TS2600 Series" "TS2600" 0x1107 600 PIXMA_CAP_CIS
#
#
# device ICLASS NAME MODEL PID DPI ADF_DPI WIDTH HEIGHT CAPACITE
device ICLASS "Canon i-SENSYS MF630 Series" "MF630" 0x27e1 600 0 637 1050 PIXMA_CAP_ADFDUP