Paragrep

- Added missing dependency on `Click` package.

- Starting with this version, `paragrep` will _only_ work on Python 3.6 or
better.
- Added type annotations.
- Updated `print` statements to use f-strings.
- Removed dependency on `grizzled-python` library. This package now requires
only the standard Python 3 library.

- Updated dependency on `grizzled-python`, to pick up a version that's
more compatible with Python 3.

- Fixed installation download URL, allowing installs from `pip` to work again.

- Added ability to display the matching end-of-paragraph lines. Specify
the "-P" option. (Issue 1, https://github.com/bmc/paragrep/issues/1)
- "-a" and "-o" options not working correctly with multiple regexs. Problem
was a Python statement indentation issue. (Issue 2,
https://github.com/bmc/paragrep/issues/2)
- Fixed some minor issues with the "-i" (case-blind) option
- Removed some dead code.

- Removed unused "-t" option from option summary in usage message.