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/V3FileLine.cpp

@@ -33,6 +33,8 @@
 #include <iomanip>
 #include <unordered_set>
 
+VL_DEFINE_DEBUG_FUNCTIONS;
+
 //######################################################################
 // FileLineSingleton class functions
 
@@ -83,12 +85,6 @@ void FileLineSingleton::fileNameNumMapDumpXml(std::ostream& os) {
 //######################################################################
 // VFileContents class functions
 
-int VFileContent::debug() {
-    static int level = -1;
-    if (VL_UNLIKELY(level < 0)) level = v3Global.opt.debugSrcLevel(__FILE__);
-    return level;
-}
-
 void VFileContent::pushText(const string& text) {
     if (m_lines.size() == 0) {
         m_lines.emplace_back("");  // no such thing as line [0]