Link correctly on mingw

Makefile to work with mingw

use gnu89 instead of ansi for mingw compat

Windows: more readable oio_write signature

Stub out check, prepare, idle, ref functions

oio_write should have a more readable sig

Minor test-loop-handles fix

Add sizes benchmark to VS project

Test for oio_prepare/oio_check/oio_idle

Update .gitignore

Replace dummy benchmark with sizeof(oio_handle)

Mac ignores

Fix bind tests for macos

tests & benchmarks - make internal stuff static

Windows: fix bugs

VS solution is missing project references

Check/prepare/idle for windows. No tests yes, so bugs are likely.

Windows: misc. fixes

Windows: implement oio_ref and oio_unref

Windows: make room for oio_handle polymorphism

Update API

Move visual studio solution/projects away from root

Closes #37

typo

api for prepare/check/idle callbacks

LF after tests complete