"Create Zotero Note from Selection" should create a webpage item automatically

[dstillman]

Option should be "Create Zotero Item and Note from Selection" instead.

My comment from the ​forum thread on this issue:

I imagine that the most common use case is to create a new note from a selection and then drag it into an item to make it a child note, which is already a two-step process and not really any easier than just right-clicking an item, selecting Add Note, and then using "Add Selection to Zotero Note." So it probably makes sense for the other option to be, essentially, "Create Zotero Item and Note from Selection," though preferably something a bit less verbose. (There may be a feature later to automatically parse a citation on a web page and create an item from it, so the text would have to be differentiated from that feature.)

[dstillman]

(In [1026]) Closes #424, "Create Zotero Note from Selection" should create a webpage item automatically

Also make "Add Selection to Zotero Note" note not add two newlines before the text if the note is empty