Skip confirmation step when editor reports no error

Instead of prompting the user to 'Press Enter to continue', drop
directly back into last view after edit when no error was reported by
the editor

References #200
Fix calculation of line number for first line in file

Commit 8c132e2a5b520754a432068dc8b1b3fcc3ab899e revealed a bug where the
editor would be opened on the second line of the file instead of the
first one due to wrong calculation of the line number.