RFR: 8244845: Lanai : J2DDemo - Clipping - Two parallel lines do not appear with AA Rendering

[Ajit Ghaisas]

Implemented DrawParalleogram method for AA rendering. Also, made DrawParalleogram and FillParalleogram methods common
for AA and non-AA rendering as all calculations are common, but only render encoders differ.

-------------

Commit messages:
 - AA DrawParalleogram implementation

Changes: https://git.openjdk.java.net/lanai/pull/115/files
 Webrev: https://webrevs.openjdk.java.net/?repo=lanai&pr=115&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8244845
  Stats: 275 lines in 3 files changed: 18 ins; 242 del; 15 mod
  Patch: https://git.openjdk.java.net/lanai/pull/115.diff
  Fetch: git fetch https://git.openjdk.java.net/lanai pull/115/head:pull/115

PR: https://git.openjdk.java.net/lanai/pull/115