Preparing for Alpha-Trim filter

Added:
- A Button object with click listener
- 2 NumericUpDown objects (Left: Window Size; Right: Trim Value)
Preparing for Alpha-Trim filter
The Class for performing the Alpha-Trim filter on a picture.

v1.0
The ENUM for choosing the sorting type for any filter.
Update README.md
Update README.md
Merge pull request #1 from chaosagex/Alpha-Trim-(Hazem)

AlphaTrim (Hazem)