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/V3Stats.cpp

@@ -28,6 +28,8 @@
 #include <iomanip>
 #include <map>
 
+VL_DEFINE_DEBUG_FUNCTIONS;
+
 //######################################################################
 // Stats class functions
 
@@ -61,7 +63,6 @@ private:
     VDouble0 m_statVarScpBytes;  // Statistic tracking
 
     // METHODS
-    VL_DEBUG_FUNC;  // Declare debug()
 
     void allNodes(AstNode* nodep) {
         m_instrs += nodep->instrCount();