Renaming should be smarter

[anthonyvdotbe]

Say I have foo(String bar, String baz), where the cursor is between z and ).
Then pressing F2 will propose to rename ).
There's 2 related issues here:

• renaming something like parentheses, commas, ... should never be possible, this doesn't make sense
• the extension should propose to rename baz, not ). Same if the cursor is between r and ,