Fix assertion violation when invoking help macro at end of help file.…

… &mid function was not safe to call on empty line, same for &mid.

Minor reformatting of help file to avoid content to be mistaken as section reference by help macro.

emacs.hlp

@@ -111,8 +111,8 @@ Pipe command ..........   ^X  @         Execute buffer ........ not bound
 Search forward ........ Meta  S     ::  End string with Meta.
 Incremental search ....   ^X  S     ::  Search next ^X, stop Meta, cancel ^G.
 Search reverse ........      ^R  
-Reverse incremental search              Hunt forward ..........  Alt-S
-.......................   ^X  R         Hunt backward .........  Alt-R
+Reverse incremental                     Hunt forward ..........  Alt-S
+                 search   ^X  R         Hunt backward .........  Alt-R
 Replace string ........ Meta  R
 Query replace string .. Meta ^R     ::  Yes/no Y/N, replace rest !, cancel ^G.
 -------------------------------------------------------------------------------
@@ -164,9 +164,9 @@ Page overlap .......... $overlap    ::  # lines, default 0, 0 = 1/3 page
 =>                      FILE NAME COMPLETION
 
 File name completion can be used with all file commands (find-file,
-view-file, ...) but it works only under UNIX and MS-DOS. It is invoked
-by a <Space> or <Tab>. If there exist more than one possible completions
-they are displayed one by one. If the file name contains wild card
-characters, the name is expanded instead of simple completion. Special
-characters can be entered verbatim by prefixing them with ^V (or ^Q).
+view-file, ...).  It is invoked by a <Space> or <Tab>.  If there exist more
+than one possible completions they are displayed one by one.  If the file
+name contains wild card characters, the name is expanded instead of simple
+completion.  Special characters can be entered verbatim by prefixing them
+with ^V (or ^Q).
 -------------------------------------------------------------------------------

eval.c

@@ -395,13 +395,8 @@ static const char *gtfun( char *fname) {
 	case UFLEFT:
 		sz1 = strlen( argv[ 0]) ;
 		sz = 0 ;
-		for( int i = atoi( argv[ 1]) ; i > 0 ; i -= 1) {
-			unicode_t c ;
-
+		for( int i = atoi( argv[ 1]) ; sz < sz1 && i > 0 ; i -= 1)
 			sz += utf8_to_unicode( argv[ 0], sz, sz1, &c) ;
-			if( sz == sz1)
-				break ;
-		}
 
 		if( sz >= ressize) {
 			free( result) ;
@@ -431,19 +426,12 @@ static const char *gtfun( char *fname) {
 	case UFMID:
 		sz1 = strlen( argv[ 0]) ;
 		int start = 0 ;
-		for( i = atoi( argv[ 1]) - 1 ; i > 0 ; i -= 1) {
+		for( i = atoi( argv[ 1]) - 1 ; start < sz1 && i > 0 ; i -= 1)
 			start +=  utf8_to_unicode( argv[ 0], start, sz1, &c) ;
-			if( start == sz1)
-				break ;
-		}
 
 		sz = start ;
-		if( sz < sz1)
-		for( i = atoi( argv[ 2]) ; i > 0 ; i -= 1) {
+		for( i = atoi( argv[ 2]) ; sz < sz1 && i > 0 ; i -= 1)
 			sz += utf8_to_unicode( argv[ 0], sz, sz1, &c) ;
-			if( sz == sz1)
-				break ;
-		}
 
 		sz -= start ;
 		if( sz >= ressize) {