SwiftJWW 1.1.0

Adds block definitions + inserts and dimensions. Block defs → DXF BLOCKs (exposed on Drawing.blocks), inserts → INSERTs, dimensions decomposed into their drawn parts. Reader parses the MFC block-definition list with correct per-definition member counts. No regression on the core line/arc/point/text path (still byte-exact vs the reference reader on real drawings). Block/dimension support validated on synthetic fixtures.