Add the posibility to show the colors of an MahApps Theme

[Megapit]

Sometimes i draw controls myself in wpf apps.
I needed an overview of used resource-colors in a theme.
Since i use this app to work with the mah icons, i feel it a good place to add color viewing.

It was a little bit quick and dirty, but works.
Sorry for some strange ways to do things. I switched over to wpf not so long ago. Also send pull request are new to me.

[Megapit]

ahhh.... learned something new.
When pulling in my local repository (Megapit/IconPacks.Browser) and allready created a pull request, then more changes will automatically added to the pull request.
That was not my plan.
So next time i want to implement new feature i have to create a new branch.
Sorry. Next time :)

[Megapit]

Anyway:
I implemented a *.ico export.

You can select the sizes you want with the checkboxes below the image.
The size of the nah-icon can be changed. It can also be rotated und translated in x/y

An Rectangle with cornerradius can also be switched on. This is not rotateable (yet? need it to be?)

Maybee this closes this issue?