Fix all sorts of incorrect double line handling in drawinglayer in order to
draw thick-thin double line types correctly.  Also change handling of border
lines in writer tables. There are still some outstanding issues but it's
much better than how it was before.

Also realized that Word and Excel handle simple thin double lines differently;
Word varies widths of all of the lines and the gap whereas Excel only has one
fixed size for its double line.  For this reason I decided to add a separate
double line type (DOUBLE_THIN) to handle Excel's double line.

Change-Id: Iaaa353b6e4f998b524262bea59260b4333e0cdb4