LEF: Implement LEF58_WIDTHTABLE

[klayoutmatthias]

For details see https://www.klayout.de/forum/discussion/2405/wrong-way-width-is-incorrect-in-def2gds-conversion

[klayoutmatthias]

The solution I implemented for now is to read the WIDTHTABLE property and take the first values of the tables (normal and WRONGDIRECTION) as the default and min width in the respective directions.