Fix buffer overflows in shortcut and workspace name handling

The handling of user defined shortcuts was not checking the length
of the shortcut before copying it to a fixed-length temporary buffer,

char buf[128];

     strcpy(buf, shortcutDefinition);

and strcpy() is well known for not checking if overflows will occur.

In particular, wmaker was crashing here if a big 'shortcut' was defined
either through WPrefs or by directly editing the configuration files.

This is now avoided by using strncpy() instead.

And this patch also fixes a similar buffer overflow for big workspace
names too.

Furthermore, use MAX_SHORTCUT_LENGTH instead of raw number and define
it to be 32 instead of 128.

src/workspace.c

@@ -54,6 +54,7 @@
 
 #include "xinerama.h"
 
+#define MAX_SHORTCUT_LENGTH 32
 
 extern WPreferences wPreferences;
 extern XContext wWinContext;
@@ -1384,7 +1385,7 @@ wWorkspaceMenuUpdate(WScreen *scr, WMenu *menu)
         i = scr->workspace_count-(menu->entry_no-2);
         ws = menu->entry_no - 2;
         while (i>0) {
-            strcpy(title, scr->workspaces[ws]->name);
+            strncpy(title, scr->workspaces[ws]->name, MAX_WORKSPACENAME_WIDTH);
 
             entry = wMenuAddCallback(menu, title, switchWSCommand, (void*)ws);
             entry->flags.indicator = 1;