org-table: Make column delete consistent with row delete

* lisp/org-table.el (org-table-delete-column): Stay in the column at
delete.  Exceptionally allow column delete when point is at eol
immediately to the right of a cell seperator.

A hint by Eric S Fraga led to this commit.
https://lists.gnu.org/archive/html/emacs-orgmode/2020-04/msg00283.html

etc/ORG-NEWS

@@ -475,6 +475,11 @@ I.e. treat the whole file as if it was a subtree.
 Before, the new column was inserted to the right of the column at
 point position.
 
+*** Table column deletion now consistent with row deletion
+
+Point stays in the column at deletion, except when deleting the
+rightmost column.
+
 * Version 9.2
 ** Incompatible changes
 *** Removal of OrgStruct mode mode and radio lists

lisp/org-table.el

@@ -1427,6 +1427,7 @@ Swap with anything in target cell."
   (interactive)
   (unless (org-at-table-p) (user-error "Not at a table"))
   (org-table-find-dataline)
+  (and (eolp) (looking-back "|" 1) (backward-char)) ; Snap into last column.
   (org-table-check-inside-data-field nil t)
   (let* ((col (org-table-current-column))
 	 (beg (org-table-begin))
@@ -1442,7 +1443,6 @@ Swap with anything in target cell."
 	 (and (looking-at "|[^|\n]+|")
 	      (replace-match "|")))
        (forward-line)))
-    (org-table-goto-column (max 1 (1- col)))
     (org-table-align)
     ;; Shift appropriately stored shrunk column numbers, then hide the
     ;; columns again.

testing/lisp/test-org-table.el

@@ -2340,6 +2340,44 @@ See also `test-org-table/copy-field'."
 	 (ignore-errors (org-table-previous-field))
 	 (char-after)))))
 
+
+;;; Deleting columns
+(ert-deftest test-org-table/delete-column ()
+  "Test `org-table-delete-column'."
+  ;; Error when outside a table.
+  (should-error
+   (org-test-with-temp-text "Paragraph"
+     (org-table-delete-column)))
+  ;; Delete first column.
+  (should
+   (equal "| a |\n"
+	  (org-test-with-temp-text
+	   "| <point>  | a |\n"
+	   (org-table-delete-column)
+	   (buffer-string))))
+  ;; Delete column and check location of point.
+  (should
+   (= 2
+      (org-test-with-temp-text
+       "| a | <point>b  | c |"
+       (org-table-delete-column)
+       (org-table-current-column))))
+  ;; Delete column when at end of line and immediately after a "|".
+  (should
+   (equal "| a |\n"
+      (org-test-with-temp-text
+       "| a | b |<point>\n"
+       (org-table-delete-column)
+       (buffer-string))))
+  ;; Delete two columns starting with the last column.
+  (should
+   (equal "| a |\n"
+      (org-test-with-temp-text
+       "| a | b  | c<point> |"
+       (org-table-delete-column)
+       (org-table-delete-column)
+       (buffer-string)))))
+
 
 ;;; Inserting rows, inserting columns