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, 3 insertions, 3 deletions

diff --git a/038new_text.cc b/038new_text.cc
index 7e3c02f6..10b819a3 100644
--- a/038new_text.cc
+++ b/038new_text.cc
@@ -31,7 +31,7 @@ if (inst.name == "new" && !inst.ingredients.empty() && is_literal_text(inst.ingr
     products.resize(1);
     products.at(0).push_back(/*alloc id*/0);
     products.at(0).push_back(new_mu_text(current_instruction().ingredients.at(0).name));
-    trace("mem") << "new string alloc: " << products.at(0).at(0) << end();
+    trace(Callstack_depth+1, "mem") << "new string alloc: " << products.at(0).at(0) << end();
     break;
   }
 
@@ -44,7 +44,7 @@ int new_mu_text(const string& contents) {
   int result = allocate(/*array length*/1 + string_length);
   int curr_address = result;
   ++curr_address;  // skip alloc id
-  trace("mem") << "storing string length " << string_length << " in location " << curr_address << end();
+  trace(Callstack_depth+1, "mem") << "storing string length " << string_length << " in location " << curr_address << end();
   put(Memory, curr_address, string_length);
   ++curr_address;  // skip length
   int curr = 0;
@@ -53,7 +53,7 @@ int new_mu_text(const string& contents) {
     uint32_t curr_character;
     assert(curr < SIZE(contents));
     tb_utf8_char_to_unicode(&curr_character, &raw_contents[curr]);
-    trace("mem") << "storing string character " << curr_character << " in location " << curr_address << end();
+    trace(Callstack_depth+1, "mem") << "storing string character " << curr_character << " in location " << curr_address << end();
     put(Memory, curr_address, curr_character);
     curr += tb_utf8_char_length(raw_contents[curr]);
     ++curr_address;