FIX: Always increment module refcount when loading [issue 268]

https://github.com/embedthis/appweb-4/issues/268
FIX: Use case-insensitive keys for the MIME types table [appweb issue 269]

https://github.com/embedthis/appweb-4/issues/269
FIX: Fix arithmetic error in mprGetTicks (windows) [appweb issue 270]

https://github.com/embedthis/appweb-4/issues/270
FIX: mprWaitForCond with no timeout [appweb issue 271]

https://github.com/embedthis/appweb-4/issues/271
FIX: WNDPROC declaration [appweb issue 273]

https://github.com/embedthis/appweb-4/issues/273