ps: unify cases and remove trailing dots in messages

Strings with lower caps & no trailing dots have greater change to
have multiple occurences, meaning less effort for translators, than
strings with them.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>

ps/select.c

@@ -60,7 +60,7 @@ const char *select_bits_setup(void){
     simple_select = 0;
     break;
   default:
-    return _("Process selection options conflict.");
+    return _("process selection options conflict");
     break;
   }
   return NULL;