Remove trailing whitespace from :column docstring

Table doctrings generated from :column algorithm no longer have trailing
whitespace
Test hydra-column-1 modified accordingly
Trimming whitespace in hydra-test.el no longer breaks non-regression

hydra-test.el

@@ -1476,8 +1476,7 @@ _h_   _l_       (O)(o)
                                  ("o" nil "ok" :column "firstcol")
                                  ("Os" 5x5-bol "outside of table 2" :column nil)
                                  ("Ot" 5x5-eol "outside of table 3")))))))
-
-#("  k         ()()
+                 #("  k         ()()
 h   l       (O)(o)
   j         (  O )
             (’’)(’’)
@@ -1491,22 +1490,22 @@ d: delete   | u: undo
 o: ok       | s: string
             | p: paste
 [Of]: outside of table 1, [Os]: outside of table 2, [Ot]: outside of table 3."
-2 3 (face hydra-face-pink)
-17 18 (face hydra-face-pink)
-21 22 (face hydra-face-pink)
-38 39 (face hydra-face-pink)
-142 143 (face hydra-face-pink)
-156 157 (face hydra-face-pink)
-170 171 (face hydra-face-pink)
-184 185 (face hydra-face-pink)
-198 199 (face hydra-face-pink)
-212 213 (face hydra-face-pink)
-226 227 (face hydra-face-blue)
-240 241 (face hydra-face-pink)
-268 269 (face hydra-face-pink)
-283 285 (face hydra-face-pink)
-309 311 (face hydra-face-pink)
-335 337 (face hydra-face-pink)))))
+                   2 3 (face hydra-face-pink)
+                   17 18 (face hydra-face-pink)
+                   21 22 (face hydra-face-pink)
+                   38 39 (face hydra-face-pink)
+                   129 130 (face hydra-face-pink)
+                   143 144 (face hydra-face-pink)
+                   152 153 (face hydra-face-pink)
+                   166 167 (face hydra-face-pink)
+                   174 175 (face hydra-face-pink)
+                   188 189 (face hydra-face-pink)
+                   196 197 (face hydra-face-blue)
+                   210 211 (face hydra-face-pink)
+                   234 235 (face hydra-face-pink)
+                   244 246 (face hydra-face-pink)
+                   270 272 (face hydra-face-pink)
+                   296 298 (face hydra-face-pink)))))
 
 
 (provide 'hydra-test)

hydra.el

@@ -1053,25 +1053,26 @@ every heads-group have equal length by adding padding heads where applicable."
        finally return decorated-heads-matrix)))
 
 (defun hydra--hint-from-matrix (body heads-matrix)
-  "Generate a formated table-style docstring according to HEADS-MATRIX and BODY data and structure
+  "Generate a formated table-style docstring according to BODY and HEADS-MATRIX data and structure.
 HEADS-MATRIX is expected to be a list of heads with following features:
 Each heads must have the same length
 Each head must have a property max-key-len and max-doc-len."
   (when heads-matrix
     (cl-loop with first-heads-col = (nth 0 heads-matrix)
-       with last-row-index = (- (length first-heads-col) 1)
-       for row-index from 0 to last-row-index
-       for heads-in-row = (mapcar (lambda (heads) (nth row-index heads)) heads-matrix)
-       concat (concat
-               (mapconcat (lambda (head)
-                            (funcall hydra-key-doc-function
-                                     (hydra-fontify-head head body) ;; key
-                                     (hydra--head-property head :max-key-len)
-                                     (nth 2 head) ;; doc
-                                     (hydra--head-property head :max-doc-len)))
-                          heads-in-row "| ") "\n")
-       into matrix-image
-       finally return matrix-image)))
+             with last-row-index = (- (length first-heads-col) 1)
+             for row-index from 0 to last-row-index
+             for heads-in-row = (mapcar (lambda (heads) (nth row-index heads)) heads-matrix)
+             concat (concat
+                     (replace-regexp-in-string "\s+$" ""
+                                               (mapconcat (lambda (head)
+                                                            (funcall hydra-key-doc-function
+                                                                     (hydra-fontify-head head body) ;; key
+                                                                     (hydra--head-property head :max-key-len)
+                                                                     (nth 2 head) ;; doc
+                                                                     (hydra--head-property head :max-doc-len)))
+                                                          heads-in-row "| ")) "\n")
+             into matrix-image
+             finally return matrix-image)))
 ;; previous functions dealt with automatic docstring table generation from :column head property
 
 (defun hydra-idle-message (secs hint name)