Moving some preparation code found at the top level of some binaries
into a prepare() sub.

Browsers seem to disagree on whether window.location.hostname
shouldinclude the brackets around an ipv6 address.
Adding PVE.Utils.windowHostname() to always strip them away.

For unknown reasons, setting queryForm: here prevents loading
the option list in the combobox.
However: the queryForm parameter only would only make sense if we also
set 'editable' to 'true', since queryForm specifies how the drop down
list should react to user input in the text field of the combobox.
Hence it is safe to remove it.

Tested with ExtJS4 and ExtJS5, this patch has no impact on
the rendering of the underneath node tree.

Ref: http://docs.sencha.com/extjs/5.1/5.1.0-apidocs/#!/api/Ext.form.field.ComboBox-cfg-triggerAction

With the alignment set to 'middle' in the north region, the 'versioninfo'
component was wrongly pushed downwards, hiding the version string.
Besides that we need to manually set a 'height' argument
to 'versioninfo' equal to the size of the north region, to prevent extjs to
generate a problematic padding.

As mentioned in
http://docs.sencha.com/extjs/5.1/whats_new/5.0/extjs_upgrade_guide.html
the 'margins' component parameter is now obsolete.

See 2489e2ab for reasoning

With ExtJS 4, we introduced an override to Ext.grid.feature.Chunking
to fix scrollings problems in the grid when having a high number
of nodes. Ext.grid.feature.Chunking has been removed from ExtJS
in version 5, so we hope either the problem is fixed on ExtJS side,
or we will have to find a different workaround.

Ext.ModelMgr.create() was removed in 5.*
The recommended way to create a new instance is to call Ext.create()
Ext.create() does not take a "id" argument, however it sets
the id of the instance to the id  of the config object given
to the Ext.create() call.