Cherry pick several changes back from 1.19.3

The main purpose of this is to backport the improved parse/runtime
errors to older versions. I think they're sufficiently useful that we
should try to make it as widely available as possible.

We've been running them for a week now on SC3 and the released version
and not seen any issues, so I think it's probably stable enough.

This is a pretty lazy commit: I ended up copying the whole ROM over and
then picking up a few other related changes along the way.

 - Trim spaces from file paths (b8fce1eecc)

 - Correctly format 12AM/PM with
   %I (9f48395596)

 - Fix http.request and htpt.websocketAsync not handling a few failure
   edge-cases correctly (3b42f22a4f).

 - Move the internal modules into the main package path, hidden under
   cc.internal (34a31abd9c).

 - Gather code coverage in Java instead of
   Lua (28a55349a9).

 - Make error messages in edit more
   obvious (8cfbfe7ceb).

 - Make mcfly's test methods global. This means we don't need to pass
   stub everywhere (7335a892b5).

 - Improve runtime and parse errors. This comes from numerous commits,
   but chiefly a12b405acf, and
   5502412181.

 - Hide the internal redirect methods in
   multishell (33b6f38339).

Note this does /not/ include the shebang changes (sorry Emma!). I've
tried to avoid adding any user-controllable features, mostly because I
don't know how to handle the versioning otherwise :).

src/test/resources/test-rom/spec/programs/cd_spec.lua

@@ -3,17 +3,17 @@ local capture = require "test_helpers".capture_program
 describe("The cd program", function()
     it("changes into a directory", function()
         local setDir = stub(shell, "setDir")
-        capture(stub, "cd /rom/programs")
+        capture("cd /rom/programs")
         expect(setDir):called_with("rom/programs")
     end)
 
     it("does not move into a non-existent directory", function()
-        expect(capture(stub, "cd /rom/nothing"))
+        expect(capture("cd /rom/nothing"))
             :matches { ok = true, output = "Not a directory\n", error = "" }
     end)
 
     it("displays the usage when given no arguments", function()
-        expect(capture(stub, "cd"))
+        expect(capture("cd"))
             :matches { ok = true, output = "Usage: cd <path>\n", error = "" }
     end)
 end)