patch 8.1.0082: in terminal window, typing : at more prompt, inserts ':'

Problem:    In terminal window, typing : at more prompt, inserts ':' instead
            of starting another Ex command.
Solution:   Add skip_term_loop and set it when putting ':' in the typeahead
            buffer.

src/main.c

@@ -1339,7 +1339,8 @@ main_loop(
 #ifdef FEAT_TERMINAL
 	    if (term_use_loop()
 		    && oa.op_type == OP_NOP && oa.regname == NUL
-		    && !VIsual_active)
+		    && !VIsual_active
+		    && !skip_term_loop)
 	    {
 		/* If terminal_loop() returns OK we got a key that is handled
 		 * in Normal model.  With FAIL we first need to position the
@@ -1348,8 +1349,13 @@ main_loop(
 		    normal_cmd(&oa, TRUE);
 	    }
 	    else
+#endif
+	    {
+#ifdef FEAT_TERMINAL
+		skip_term_loop = FALSE;
 #endif
 		normal_cmd(&oa, TRUE);
+	    }
 	}
     }
 }
@@ -3320,7 +3326,7 @@ usage(void)
     main_msg(_("-dev <device>\t\tUse <device> for I/O"));
 #endif
 #ifdef FEAT_ARABIC
-    main_msg(_("-A\t\t\tstart in Arabic mode"));
+    main_msg(_("-A\t\t\tStart in Arabic mode"));
 #endif
 #ifdef FEAT_RIGHTLEFT
     main_msg(_("-H\t\t\tStart in Hebrew mode"));