Log Message:
todotxt: Update time/todotxt to 2.11.0

pkgsrc changes:
 - Add support for the test suite (this needs gmake as a test tool dependency)
 - Fix the shebang of test shell script with REPLACE_BASH and also add a
   SUBST to fix a shebang in the middle of scripts (needed in shell script part
   of the test suite).
   REPLACE_INTERPRETER only adjust the shebang in the first line of the file.
 - Add patches/patch-tests_test-lib.sh to just use `date -r' in non-GNU and
   non-macOS lands. By default the current date is used and then the test will
   definitely fails. While there are no guarantees that the date(1) available on
   the system supports `-r' option it is probably better to try using it (indeed
   this make all the date tests happy on NetBSD and probably also on FreeBSD and
   OpenBSD according a quick skim of their date(1) man pages).
 - Also install USAGE.md document (it is referenced by README.md).

Changes:
## [2.11.0] - 2018-03-26
### Added
- Added support for `$XDG_CONFIG_HOME` config file/actions location
- Created [CODE_OF_CONDUCT.md](/CODE_OF_CONDUCT.md) ([#217])
- Created [CHANGELOG.md](/CHANGELOG.md) ([#218])

### Changed
- Updated `add` command to accept lowercase priority ([#230])
- Clean tests and version file in Makefile. Don't ignore errors in tests.
- Updated [README.md](/README.md) ([#219])
- Update Downloads links to point at the Releases page ([#228])
- Set the executable bit when preparing releases ([#156])

### Fixes
- Update links to use https
- Suppress todo.sh error messages when invoked during completion ([#8])