bug fixes

[yassersouri]

• when updating the line end points, also update the line end points in the layers panel.
• change the color on the layer when selected, currently it is not readable.
• when already added a line select it by default.
• when ctrl-s is pressed change the color in images panel.
• don't save empty files.
• Fix the boundary issue that cause's few UI operations to be out of place
• Clip line endpoint coordinates to the image boundary

[yassersouri]

@erfannoury please do these ASAP.

[erfannoury]

First bug in the list of bugs has been resolved, but the new implementation is not yet complete. There is still problem remaining with the Multibinding.
Since this bug is not serious, a release without complete fix to this specific bug will be published.

[yassersouri]

Nice features! Thank you.