Use cell for addresses, not ucell
Add amx_types.h
Remove redundant fractional parts in JSON output

Due to the use of std::fixed all integer numbers had trailing
".0000". Also removed std::setprecision manipulators - the output
of the JSON writer is not supposed to be read by humans directly
(because there are HTML and text writers for that purpose) but
rather fed into some sort of parser that may perform various
computations on the numbers present there, and truncating them
can have negative effects on the results.
Fix output stream's fixed flag not being reset

The std::fixed manipulator appears to be not reset before next
operation, unlike std::setprecision, so apparently it has to be
set only once and reset to its previous value when we are done
with the stream.
Change underlying duration type from double to long double
Fix too short horizontal line in text output

The number of columns has changed recently, so update the kNumColumns
constant accordingly. Also while we are here, remove the unused kTypeCol
constant.
Remove self_time_percent and total_time_percent properties

They can be easily calculated from self_time and total_time.
Use camelCase for property names

This appears to be the most widely used naming convention in JSON, so
it seems like a good idea to adhere to it.
Extend EscapeString() to work with more escape chars

Now it works not only with backslashes, but also all JSON-recognized
control characters and quotes (according to www.json.org).
Add missing #includes in statistics_writer.h
Improve console messages