Fix #185 (donot indent_after_task if auto_complete)
Fix #187 (avoid multiline header, non-greedy regex)

unbelievable, but \s* consumes new line; so it should be non-greedy \s*?
Added priority feature close #188 fix #44
Update readme, tutorial, install.txt

formatting, typos, update contributors list, etc.
Fix #187 (regression); fix NewCommand

• header has to match new line for full width background, so split
multiline headers programmatically;
• because header match new line, NewCommand may decide it is header
while it is completely empty line
Fix #189 (default values); Fix #191 (update readme)
Fix #190 (allow single char header)
Added new scheme tasks-eighties-colored close #192