Optimization

[narnaud]

perf: Use a query for toggling section

This is faster than getting all the symbols, as we don't need to do any
kind of processing of the symbols.

perf: Optimize symbols creation

No need to get the text from the document every time, this reduce the
complexity a lot.
Also squeeze the text from the range, to avoid using too much memory (as
the string is the size of the file).

perf: Bypass logger if it's not needed

We don't need to do anything if we can't log, so bypass the logger
entirely.
Also bypass a copy of the file during TextDocument::text(), as it's not