Remove a weak_alias that results in a build error in some configs.

Notably, this was a build error for IMVU.
Update indexes (and associated changes) for most of remaining sections
Remove temporary scratchpad files
move Debugging topic up level (no longer in index)
Remove ready-to-review on checked index documents.
fix stringToC so it is parseable again
default emcc help to mention emcc, mention ./emcc just once
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Merge pull request #2749 from waywardmonkeys/fix-vfscanf-weak-alias

Remove a weak_alias that results in a build error in some configs.
fix emscripten ifdef
Merge pull request #2755 from hamishwillee/incoming

Incoming - additional index topics updated
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[tracing] Initial tracing API.

This is used in conjunction with a collection & analysis server
to analyze memory usage and other aspects of a program running
under emscripten.
[tracing] Integrate the tracing stuff.
[tracing] Instrument dlmalloc.c

These changes compile out entirely if tracing is not enabled.
[tracing] Initial trace collection server.