* Apply Dick's patch along with a few minor changes to fix some clashes with
changes in my branch. Thanks Dick!
* Added missing DRAWSEGMENT line angle.
* Fix thru hole pad layer mask issue.
* Add s-expression file parser object and keyword files.
* Fix minor issues with s-expression file formatting.
* Fix a minor bug the zone container fill state parsing in the legacy plugin.
* Move EDA_TEXT visibility definition to eda_text.h.
* Add minor BOARD_ITEM object improvements to support s-expression file
parser.