Fix #403.  Exit TempVisualMode (return to InsertMode) when selection is
cleared.
Update unstable update site.
Perform an 'organize imports' project-wide.
Make an entire macro execution a single undo-able operation.
Fix #404.  Add support for ':let @<char>=' to set register contents
directly.
Update unstable update site.
#404.  Handle quoted strings when parsing 'let'.
Test fix for last line selection UI.