Before this commit, if a matrix was lacking one element, some ugly errors appeared to the user.
Now, it just displays the empty cell and lets the user go on.
Also, acknowledge another limitation of the widget and add it to roadmap.
Declare as many options prefixed with this string as you need for binding
a field value with an HTML node attribute (disabled, class, style...)
called as the `<name>` passed in the option.
NOTE: This doesn't prevent to require to fill the full matrix with
all the combination records.
* README update to newest OCA template
* Example in README
* Massive performance boost for big matrices, specially on Firefox
* Assign id on row in order to find it back in all cases
* Fix#321, choked on cached writes
