Dead keys

[TheLastRar]

Retrieves the character for a dead key, and marks the character as a Dead Key.

The information regarding DeadKeys can be found here;

WPFKeyboard/Headers/kbd64.h

Lines 344 to 369 in 3a36008

	/***************************************************************************\
	*
	* VK_TO_WCHARS64<n> - Associate a Virtual Key with <n> UNICODE characters
	*
	* VirtualKey - The Virtual Key.
	* wch[] - An array of characters, one for each shift state that
	* applies to the specified Virtual Key.
	*
	* Special values for VirtualKey:
	* -1 - This entry contains dead chars for the previous entry
	* 0 - Terminates a VK_TO_WCHARS64[] table
	*
	* Special values for Attributes:
	* CAPLOK - The CAPS-LOCK key affects this key like SHIFT
	* SGCAPS - CapsLock uppercases the unshifted char (Swiss-German)
	*
	* Special values for wch[*]:
	* WCH_NONE - No character is generated by pressing this key with the
	* current shift state.
	* WCH_DEAD - The character is a dead-key: the next VK_TO_WCHARS64[] entry
	* will contain the values of the dead characters (diaresis)
	* that can be produced by the Virtual Key.
	* WCH_LGTR - The character is a LIGATURE64. The characters generated by
	* this keystroke are found in the LIGATURE64 table.
	*
	\***************************************************************************/

I included support for both 32bit and 64bit OS, however I've only tested on a 64Bit OS, so I can't verify that the 32bit code is functional.

I've also not updated the pre-built WindowsKeyboardLayout.dll files in the repo, as I didn't have the older toolkits/SDKs (I had upgraded locally), so you will need to commit updated builds if you merge this PR