Start re-working the HTML report

[better viewed with -w or -w --word-diff]

- add header with report generation time
- better color scheme
- make callers/callees metadata more visually distinct, and reword
  its description
- fix empty <a> tag, which can't be self-closed
- add DOCTYPE
More TODO
Test the that the total sample value is correct
Only ignore MYMETA.* files

Otherwise META.* they are not included in the release tarball...
Generate META.json in addition to META.yml
Add repository metadata to META.*
Break ties in sub sorting by comparing inclusive times
No change, only reflow long lines
Make the test test what it says in the description
Only use trampoline runloop when profiling is enabled at startup

Reverts a change introduced by 6a7645f96cb2f1c04234da8fc48841e (not really a
bug because the tracing works correctly in both cases).

Apart from reducing unintended side-effects on load, it simplifies tesing the
normal runloop -> tracing runloop (without trampoline) code path.