Fix cursor problem when deleting mentions

[wtr7]

Answer on issue #94. @jfschwarz

If I'm correct we should always set the cursor at the right position when the component did update. Currently there's a boolean called setSelectionAfterMentionChange that I believe is not needed. This boolean is initialised as false but when we open the examples we have standaard mention tags. When we then delete them, the cursor doesn't get to the right place because setSelectionAfterMentionChange is false. By not checking for setSelectionAfterMentionChange the cursor always gets to the right place of deleting.

[jfschwarz]

The setSelectionAfterMentionChange is used to prevent unnecessarily setting the selection, which might cause issues with complex inserts (e.g. see #40).

Receiving this PR, however, gave me the motivational push to further investigate the issue. :) I found a fix, which has been released with version 0.6.1

Thank you!