Log Message:
cmark: updated to 0.28.3

[0.28.3]
* Include GNUInstallDirs in src/CMakeLists.txt.
  This fixes build problems on some cmake versions.

[0.28.2]
* Fixed regression in install dest for static library.
  Due to a mistake, 0.28.1 installed libcmark.a into include/.

[0.28.1]
* --smart: open quote can never occur right after ] or ).
* Fix quadratic behavior in finalize (Vicent Marti).
* Don't use CMAKE_INSTALL_LIBDIR to create libcmark.pc.
  This wasn't getting set in processing libcmark.pc.in, and we
  were getting the wrong entry in libcmark.pc.
  The new approach sets an internal libdir variable to
  lib${LIB_SUFFIX}.  This variable is used both to set the
  install destination and in the libcmark.pc.in template.
* Update README.md, replace make astyle with make format