Add conver_db/ directory to .gitignore.
Add tests.
Fix 'color' parameter default value in doc.
Simplify code (remove 'color_random' parameter).
Remove trailing whitespace from code.
Add test for constructor.
Rewrite word "Suffix" to "Image type" in error message.
Fix 'type' parameter default value in doc.
Release 0.06 version.
Prepare for 0.07 version.