Complete LEF support

[nanobowers]

LEF Library support is incomplete, would be useful to be able to read/write all LEF5.8 constructs within reason.

Library Level

• [ ] NONDEFAULTRULE
• [ ] MANUFACTURINGGRID
• [ ] PROPERTYDEFINITIONS
• [ ] CLEARANCEMEASURE
• [ ] VIARULE
• [ ] VIARULE GENERATE
• [ ] LAYERS
• [ ] MAXVIASTACK
• [ ] SITE with ROWPATTERN
• [ ] FIXEDMASK
• [ ] Extensions (BEGINEXT → ENDEXT)

Macro Level

• [ ] PROPERTY
• [ ] DENSITY
• [x] FIXEDMASK
• [x] EEQ

Pin Level

• [x] TAPERRULE
• [x] NETEXPR
• [x] SUPPLYSENSITIVITY
• [x] GROUNDSENSITIVITY
• [x] MUSTJOIN
• [ ] PROPERTY

Geometry Level

• [ ] ITERATE support
• [ ] MASK value > 2
• [ ] MASK for POLYGON and PATH