Don't display error messages and try other providers when the user
cancels loading a file.
Remove files from the MRU lists if they can't be found.
Closes#717.
Originally committed to SVN as r4717.
* Wrapping all headers that are in agi_pre.h with AGI_PRE.
* Sorting alphabetically.
* Same operation as r3515.
Note: This is broken when precompiled headers are not in use, I'll fix that after this commit so the two changes don't get jumbled up.
Originally committed to SVN as r3525.
* Update agi_pre.h to include some missing headers, also move required windowsheaders to the top of the list
* Use <> versus "" for the wx header in avisynth_wrap.cpp
* Remove xx/wx.h from agi_pre.h as it's included by wxprec.h.
Originally committed to SVN as r3513.
* Remove include guard in main.h as it's no longer required.
* Sort wx headers and wrap with #ifndef WX_PRE.
* Add #define WX_PRE to stdwx.h.
Originally committed to SVN as r3502.
Tested on OSS4 (4front), FreeBSD 7.2 OSS and with ALSA's OSS emulation.
Bear with me, this is both my first serious C++ and OSS code.
Originally committed to SVN as r3497.
