This also fixes an issue where MIDI CI header data could contain spaces,
which is not allowed according to the spec.

This fixes a bug where moving a window between displays with different
scaling settings makes the embedded WebView misaligned.

Prior to this change all <tspan> elements without x, and y attributes would
just inherit the parent elements such attributes and be placed in the same
location. This didn't respect whether these attributes were consumed already
by the parent.

Having multiple x and y elements, or having a different number of x and y
elements was also not handled in line with the rules for SVG.

This change affects the DatagramSocket and StreamingSocket classes.

- Also refactored internals to use weak/shared pointers

This allows the LookAndFeel of submenus to query the target component
used for the top-level menu. getTargetComponent() isn't suitable for
this because the target component is set to null for submenus, and this
behaviour can't be changed without potentially breaking code that relies
on the current behaviour.

This fixes a bug, where VoiceOver would interact with the InnerNSView in
the AudioPluginHost. Instead the focus now jumps from the minimise
button directly to the plugin's first accessible element.

On MacOS the rule is: when returning accessibilityChildren an ignored
child must be replaced with its own children. When returning the
accessibilityParent, an ignored element must be replaced with its own
parent.

This makes it consistent between Windows and MacOS. This is restoring
the behaviour prior to 7e404118b5.