4987 - support `browse_trace` tool in SubX

I've extracted it into a separate binary, independent of my Mu prototype.

I also cleaned up my tracing layer to be a little nicer. Major improvements:

- Realized that incremental tracing really ought to be the default.
  And to minimize printing traces to screen.

- Finally figured out how to combine layers and call stack frames in a
  single dimension of depth. The answer: optimize for the experience of
  `browse_trace`. Instructions occupy a range of depths based on their call
  stack frame, and minor details of an instruction lie one level deeper
  in each case.

Other than that, I spent some time adjusting levels everywhere to make
`browse_trace` useful.

1 files changed, 1 insertions, 1 deletions

diff --git a/043space.cc b/043space.cc
index d348f736..6028ef0d 100644
--- a/043space.cc
+++ b/043space.cc
@@ -264,7 +264,7 @@ void check_default_space(const recipe_ordinal r) {
   // End check_default_space Special-cases
   // assume recipes with only numeric addresses know what they're doing (usually tests)
   if (!contains_non_special_name(r)) return;
-  trace(9991, "transform") << "--- check that recipe " << caller.name << " sets default-space" << end();
+  trace(101, "transform") << "--- check that recipe " << caller.name << " sets default-space" << end();
   if (caller.steps.empty()) return;
   if (!starts_by_setting_default_space(caller))
     raise << caller.name << " does not seem to start with 'local-scope' or 'default-space'\n" << end();