mc/edit-lines: Don't include the 'invisible' line

- when marking a region from bottom to top there is an invisible line
   in the region if mark is at the beginning of the line.
 - don't count that line when doing mc/edit-lines

features/edit-lines.feature

@@ -18,6 +18,18 @@ Feature: Switching from a multiline region to multiple cursors
     And I press "C-S-c C-S-c"
     Then I should have 2 cursors
 
+  Scenario: Edit lines from bottom up
+    When I insert:
+    """
+    hello
+    there
+    """
+    And I go to the front of the word "there"
+    And I set the mark
+    And I go to the front of the word "hello"
+    And I press "C-S-c C-S-c"
+    Then I should have one cursor
+
   Scenario: Edit only real lines, even in visual-line-mode
     Given I turn on visual-line-mode
     And I insert:

mc-edit-lines.el

@@ -38,13 +38,18 @@ line point is on."
   (when (not (use-region-p))
     (error "Mark a set of lines first."))
   (mc/remove-fake-cursors)
-  (let* ((point-line (line-number-at-pos))
+  (let* ((col (current-column))
+         (point-line (line-number-at-pos))
          (mark-line (progn (exchange-point-and-mark) (line-number-at-pos)))
          (direction (if (< point-line mark-line) :up :down)))
     (deactivate-mark)
+    (when (and (eq direction :up) (bolp))
+      (forward-line -1)
+      (move-to-column col))
     (while (not (eq (line-number-at-pos) point-line))
       (mc/create-fake-cursor-at-point)
-      (if (eq direction :up) (forward-line -1) (forward-line 1)))
+      (if (eq direction :up) (forward-line -1) (forward-line 1))
+      (move-to-column col))
     (multiple-cursors-mode)))
 
 ;;;###autoload