Image optimizations for our image resources.

The png files were otimized with 'pngcrush -brute' and the gif with 'gifsicle'.
The changes -- although they are supposed to be lossless -- should be tested in
different browsers.
Remove wrong parameter description in init-method

Thanks for catching this, Gary White.
Use Ext.Array.indexOf not Array.prototype.indexOf.

This is especially important for e.g. IE 8, where the native array does not have the indexOf method.
Remove aliasing to a global variable.
Merge pull request #165 from marcjansen/remove-global

Remove aliasing to a global variable. (r=@bartvde)
Respect config options constrain/constrainHeader.

The draggeing behaviour of instances of Ext.window.Window
usually can be configured with e.g. `constrain` or `constrainHeader`.
Since our gx_popups usually start pinned to a location and get their
dragging behaviour added when they are unpinned, those config options need
to be passed to our dynamically created dd-object.
Optionally constrain gx_popup in example.
Adjust win positioning as suggested by @chrismayer
Merge pull request #166 from marcjansen/popup-constrain

Respect config options constrain/constrainHeader (r=@chrismayer)
Add license header to PrintPageField.js & View.js.
Adjust copyright to 2013.
Merge pull request #167 from marcjansen/copyright-year

Adjust the copyright year
Update src/GeoExt/tree/LayerContainer.js

Removed error in API-Docs example code
Fix DOS line endings
Compatibility fix for ExtJS 4.2
Merge pull request #171 from m-click/fix-line-endings

Fix DOS line endings
Replaced native indexOf() with Ext.Array.indexOf()

Replaced native indexOf() method with Ext.Array.indexOf() to gain compatability with IE8.
Merge pull request #172 from buehner/patch-1

Replaced native indexOf() with Ext.Array.indexOf()
Merge pull request #170 from m-click/fix-extjs-4.2

Compatibility fix for ExtJS 4.2
Merge pull request #152 from marcjansen/pngcrush

Image optimizations for our image resources.