fix soname
update for 2.1.1 stable release
fix soname to use CS_API_MAJOR for library versioning (linux)
update ChangeLog & RELEASE_NOTES for 2.1.1
make dist should also generate ZIP file
package: update Brew formula to upstream version
package: upgrade Brew package to 2.1.1
delete some orphan files
package: update Brew formula
core: fix some warnings
Makefile: fix SONAME