Bump version: 0.2.6-dev → 0.3.0-dev

Release Note:

1. Merge Implement async functionality #47 by JeffLIrion
2. Merge Check the length of the screencap before indexing into it #53 by JeffLIrion
3. Remove python 2 support

Bump version: 0.2.5-dev → 0.2.6-dev

Bump version: 0.2.4-dev → 0.2.5-dev

Bump version: 0.2.3-dev → 0.2.4-dev

Bump version: 0.2.2-dev → 0.2.3-dev

Fix typo

Bump version: 0.2.1-dev → 0.2.2-dev

Bump version: 0.2.0-dev → 0.2.1-dev

Bump version: 0.1.6-dev → 0.1.7-dev

Bump version: 0.1.5-dev → 0.1.6-dev