Remove excessive shortcut key matching in ToolStrip

This fixes https://bugzilla.xamarin.com/show_bug.cgi?id=23532.
Fix potential crash in ListView.ItemControl.ItemsMouseDown

This fixes Xamarin bug 23591.  Side-effects of internal processing of
ItemsMouseDown can cause ItemsMouseUp before ItemsMouseUp has finished.
Test DataTable.ReadXmlSchema with non Schema base element. Covers #22501.
DataTabe.ReadXmlSchema now handles non Schema base element. Fixes #22501.
Implement MachineKey.Protect and MachineKey.Unprotect
Fix bugs in sizing TableLayoutPanel (Xamarin bug 18638)

Consider spans and absolute sizes in computing PreferredSize for
TableLayoutPanel.
Also fix bug in allocating unused width to SizeType.Absolute columns.

Change-Id: Ic5065b83ced8195d1c5be39087f33b0d632fc9a6
[cleanup] System.Web*: remove TARGET_J2EE

done using unifdef
git grep -l TARGET_J2EE | grep -v ChangeLog | xargs -n1 unifdef -m -UTARGET_J2EE

Signed-off-by: Etienne CHAMPETIER <etienne.champetier@fiducial.net>
[cleanup] WebConfigurationManager: remove hasConfigErrors

it's not used since 2009 (6a261e04add13efa6eb43ed015ab26953c2b3a95)

Signed-off-by: Etienne CHAMPETIER <etienne.champetier@fiducial.net>
[System.Core] Bring .NET implementation of ReaderWriterLockSlim.
[System.Core] Removed no longer used files.
System.Core is now using .NET implementations of LockRecursionPolicy and ReaderWriterLockSlim.
[msvc] Fixed missing semi-colon.
Removed some dead code.
[msvc] Fixed empty struct declaration (it's not valid C according to MSVC).
[msvc] Updated project files.
[msvc] Fixed heap problems at runtime when calling free().

Due to an incompatibility in the project files and DLL API setup code, we were importing locally defined symbols as DLL. This manifested as a debug heap dialog in VS caused by allocating and freeing memory between two Windows modules (which have their own memory heap).

Fix this by simplifying the DLL defines in MSVC, we are relying on .def files to manually specify the exports anyway.
[driver] Fixed outdated URL in help message.
[mcs] Add support for __refvalue passed as a reference
[mcs] At least one of nameof methodgroup argument candidates needs to be accessible
[mcs] Improve extension methods error reporting
[System.Web.DynamicData] Fixed test to verify the right behavior

The exception that is thrown is now consistent with MS.NET due to the imported System.ComponentModel.DataAnnotations code.