Gets the x and y positions and justification for a legend or table in user units from the string descriptors like "top".
get.tablepos(x)A valid position descriptor like "top".
A list containing:
x position
y position
x (horizontal) justification
y (vertical) justification
get.tablepos checks for one of the nine valid position descriptors:
topleft, top, topright, left, center, right, bottomleft, bottom and bottomright.
If none of these descriptors are found, it will return the center position and justification.