Add Rows and Columns properties to UniformGrid

[DoubleDBE]

Coming from #122

In WPF, we have the ability to specify how much rows and columns the UniformGrid must generate.

eg <UniformGrid Rows="1" Columns="2"/>

This gives us more control on how the UniformGrid should behave.

As explained in the WPF documentation:
A value of zero (0) for the Rows property specifies that the row count is computed based on the number of columns and the number of visible child elements that are in the grid.

A value of zero (0) for the Columns property specifies that the column count is computed based on the number of rows and the number of visible child elements that are in the Grid.

This means that by adding these properties, the current behaviour won't be affected and developers coming from XCT won't have any issues porting over to MCT since the UniformGrid should behave as-is when these properties are not specified.

For completeness sake, we could also add the FirstColumn property although i've never used that property ever before.

[VladislavAntonyuk]

I suggest renaming it to MaxRows and MaxColumns. by default both values contain int.MaxValue. if the value is set for any of these properties we will calculate based on the value

[VladislavAntonyuk]

You can track implementation in this PR: #139

[DoubleDBE]

Awesome!

[CliffAgius]

Closed as merged.