upgrading version and readme

readme, proguard

Merge pull request #417 from peterLaurence/fix#415

Fix#415

bumping version

Merge pull request #371 from moagrius/issue/221

issue-221 dont draw recycled bitmaps

bumping version

bumping version

Merge pull request #341 from moagrius/bug/339-340

Bug fixes for 339 and 340

updating readme

Merge pull request #325 from moagrius/release/2.2.0

using a single canvas