Adding support for iconset version change

[ms92ita]

Hello,

to complete the plugin functionalities, I think that it misses a function like "setIconsetVersion", that changes the version.
I have encountered this because I offer different iconset to choose for my customers and some of these do not use the last version, so in addition to "setIconset", it can be great extend the function with the version and/or define a new function like "setIconsetVersion"

Cheers