i have another release for you all ;-)

This time its a short but important release which contains a fix bugfixes and two new things.
On Linux/X11 key release messages was never detected properly, so i fixed that finally.
I added support for dragging and dropping a single file into the window, but only for win32 for the moment (X11 will come soon).
Also i added a new init flag (fplInitFlags_Console) to control when a console gets created. I did that because the detection was not properly working.

Oh and before i forgot, i finally finished the image viewer demo.
Its not perfect, as i cannot render images such as https://libfpl.org/blog/grid_render_test.png but it works for most images, so i am happy. I even made and set a icon, including the .RC shit for MSVC.

Thats it. The next release will definitily take a while, as i am sick like shit and barely can type.

As usual the release is tagged and documentations are updated.

Here is full changelog:

## v0.8.4.0 beta:
- New: Added macro function FPL_STRUCT_INIT
- New: Added enum value fplWindowEventType_DropSingleFile
- New: Added structure fplWindowDropFiles
- New: Added enum value fplInitFlags_Console
- New: [Win32] Support for WM_DROPFILES -> fplWindowEventType_DropSingleFile event
- Changed: Move fplInitFlags_All out and made it a static constant
- Changed: Use fplInitFlags_Console to activate console or not
- Fixed: fplExtractFileExtension was returning wrong result for files with multiple separators
- Fixed: [Win32] Fullscreen toggling was broken in maximize/minimize mode
- Fixed: [Win32] ClientToScreen prototype was missing WINAPI call
- Fixed: [POSIX] fplListDirNext() was broken
- Fixed: [X11] Key up event was never fired (KeyRelease + KeyPress = Key-Repeat)