Win32: Map ERROR_DIRECTORY to ENOTDIR. Fixes [Bug 7271].
mkpeep: Fixed warning.
IOBuffer: Added try_read().

This is an analogue to Stdio.File()->read().
Do not trigger the write callback again when nothing is written

This saves the user from checking sizeof(buffer) before doing buffer->output_to(...)
No, actually, it is not reached.

This saves a few bytes of binary size. :)
Fixed the read and write callback types.

This makes them more usable in strict_types mode.

Since the types are now so long they use a typedef.
Allow adding chunks bigger than 2^32 at a time using add() and friends.

Also, instead of saying you are trying to read too much when reading -<whatever> bytes
using read or try_read you will now get an error indicating you are reading a negative number of bytes, which is hard.

I guess it might unread(), but that would be highly unexpected.
Fixed signed/unsigned warning
Updated the Parser.HTML testsuite

It now assumes that ending a quote also ends the argument (or attribute name).

We are still very far from a true HTML5 parser, but at least this makes
parsing live websites somewhat possible (as an example, yandex.ru had

<tag style=...id=...>)
Do not show compile errors for tests testing compile errors.