Add more flexibility with input layer (implemented already)

[yannikw0]

Hi,

I played around with the script a little bit to add more flexibility to the processing of the currently selected layer.

• Option "Name from layername": I removed the "string field value" as an obligatory input for the plugin to work. In my edited script I added an option to create poylfilenames from the layername and the feauture id. This also works if there are no fields at all in the current layer.

• Option "Name from field value": I changed the pre-selection of fields to checking if the values in the fields are unique and not empty. This is important since in the current script all values in a string field can be the same value which will result in overwriting the output poly file. The fieldtype now could also be an integer or another datatype tha tallows unique values.

• Communication: Lastly I changed the way the plugin communicates with the user. There is just one pop-up-window with all the info and options together with an output folder path selection. I'll include a screenshot here:
  

Are you interested in my edits or parts of it? I can make a fork and a pull request out of it.