Move TIP 280 and command extent housekeeping to the periphery.
Plug memory leak;  Break three compilation mechanisms into routines.
Unbreak MSVC6 debug build (thanks Andreas Kupries!)
Unbreak MSVC6 debug build (thanks Andreas Kupries!)
Factor out compiling the Command literal.
merge trunk
Use TIP 280 macros.
Use the TokenAfter() macro.
Tentative Work In Progress unwinding TIP 280 line information.
Revise the litInfo table so that it gets built later (in TclInitByteCodeObj)
from a simpler store of data that can unwind.
Remove the (now unused) wlineat arguments.
Disabling the SetLineInformation() macro entirely causes only 3 tests
in the test suite to fail.  Restoring just 2 SetLineInformation() calls
fixes those failures.  The need for all the other SLI() calls is not
demonstrated by any test.  Without more complete test coverage, it is
difficult to confidently tweak the TIP 280 implementation without fear
that changes are introducing breakage.
First additional test.  Remove dup macros in tclEnsemble.c.
Next attempt.  Appears to have uncovered a bug.
Fix for [86fb5ea28e].  Test will eventually merge in from tip280-test-coverage.
merge trunk
Add tests for, and fix bugs in, the SetLineInformation() calls in tclCompCmds.c.
Add tests for SetLineInformation() calls in tclCompCmdsGR.c.
Add tests for SetLineInformation() calls in tclCompCmdsSZ.c as well as some
obvious refactoring improvements.
Add tests for the SetLineInformation() calls in tclEnsemble.c, and fix
the bugs around those calls exposed by the tests.