MAGN-728 Fixed Zoom is not working (using scroll) after opening attached file.

Issue: EndlessViewModel didn't take X and Y into consideration at the start.
Opening save file can start at the "saved position" for the workspace.
MAGN-701 Fixed "New workspace does not start at it's offset and zoom"

Issue: Newly created WorkspaceView's offset and zoom is not based on its WorkspaceModel's attributes.

This issue causes shortcut function of pan or zoom to jump. As those function make use of
WorkspaceModel's attributes for its operation.

It also causes EndlessGrid to appear at the wrong position, causing infinite canvas feature to fail.

This commit fixes them.
MAGN-687 Fixed canvas manipulation interface not working in Custom node workspace
Merge pull request #756 from l2obin/CanvasControlFixes

Fix for MAGN-687, MAGN-701, MAGN-728