Streamline dump control options

- Rename `--dump-treei` option to `--dumpi-tree`, which itself is now a
  special case of `--dumpi-<tag>` where tag can be a magic word, or a
  filename
- Control dumping via static `dump*()` functions, analogous to `debug()`
- Make dumping independent of the value of `debug()` (so dumping always
  works even without the debug flag)
- Add separate `--dumpi-graph` for dumping V3Graphs, which is again a
  special case of `--dumpi-<tag>`
- Alias `--dump-<tag>` to `--dumpi-<tag> 3` as before

src/V3VariableOrder.cpp

@@ -34,6 +34,8 @@
 #include <algorithm>
 #include <vector>
 
+VL_DEFINE_DEBUG_FUNCTIONS;
+
 //######################################################################
 // Establish mtask variable sort order in mtasks mode
 
@@ -205,5 +207,5 @@ void V3VariableOrder::orderAll() {
          modp = VN_AS(modp->nextp(), NodeModule)) {
         VariableOrder::processModule(modp);
     }
-    V3Global::dumpCheckGlobalTree("variableorder", 0, v3Global.opt.dumpTreeLevel(__FILE__) >= 3);
+    V3Global::dumpCheckGlobalTree("variableorder", 0, dumpTree() >= 3);
 }