date/time prompt: Provide support for HHhMM time input

* lisp/org.el (org-read-date-analyze): Add support for HHhMM time
input, in similar way as for am/pm times.
* doc/org-manual.org (The date/time prompt): Add example to illustrate
the feature.

TINYCHANGE

doc/org-manual.org

@@ -6060,6 +6060,7 @@ dash(es) as the separator in the former case and use =+= as the
 separator in the latter case, e.g.:
 
 | =11am-1:15pm=  | \rArr{} 11:00-13:15   |
+| =11h-13h15=    | \rArr{} same as above |
 | =11am--1:15pm= | \rArr{} same as above |
 | =11am+2:15=    | \rArr{} same as above |
 

lisp/org.el

@@ -14104,6 +14104,19 @@ user."
 	       (setq ans (replace-match (format "%02d:%02d" hour minute)
 					t t ans))))
 
+    ;; Help matching HHhMM times, similarly as for am/pm times.
+    (cl-loop for i from 1 to 2 do	; twice, for end time as well
+	     (when (and (not (string-match "\\(\\`\\|[^+]\\)[012]?[0-9]:[0-9][0-9]\\([ \t\n]\\|$\\)" ans))
+			(string-match "\\(?:\\(?1:[012]?[0-9]\\)?h\\(?2:[0-5][0-9]\\)\\)\\|\\(?:\\(?1:[012]?[0-9]\\)h\\(?2:[0-5][0-9]\\)?\\)\\>" ans))
+	       (setq hour (if (match-end 1)
+				(string-to-number (match-string 1 ans))
+			      0)
+		     minute (if (match-end 2)
+				(string-to-number (match-string 2 ans))
+			      0))
+	       (setq ans (replace-match (format "%02d:%02d" hour minute)
+					t t ans))))
+
     ;; Check if a time range is given as a duration
     (when (string-match "\\([012]?[0-9]\\):\\([0-6][0-9]\\)\\+\\([012]?[0-9]\\)\\(:\\([0-5][0-9]\\)\\)?" ans)
       (setq hour (string-to-number (match-string 1 ans))