String safety (#1548)

* Array size UB fixes

* Fix ShieldD

* Remove (almost) all unsafe strcpy calls

Bunch of macros. C arrays are easy enough and just need a different call. For various cases where a char* is passed around bare, I've made a TEXT_SPAN macro that can store a length too for bounds checking.

* Move crash handling in safe string operations to separate TU

* strcat safe version

* sprintf made safe too

* Fix compile

src/d/d_debug_camera.cpp

@@ -1349,11 +1349,11 @@ void dDbgCamera_c::monitor() {
 
         for (var_r27 = 0; var_r27 < 4; var_r27++) {
             if (var_r27 == mCmdMode) {
-                strcat(spC0, "____ ");
+                SAFE_STRCAT(spC0, "____ ");
                 break;
             }
 
-            strcat(spC0, "     ");
+            SAFE_STRCAT(spC0, "     ");
         }
 
         Report(pos_x, pos_y, 7, "    %s", spC0);