Merge pull request casbin#529 from divy9881/add_cpp_support

fix: add cpp in supported languages.

fix: duplicated policies inside rules to add (casbin#526)

Signed-off-by: Cheng JIANG <jiang.cheng@vip.163.com>

fix: Add DeleteRolesForUserInDomain (casbin#523)

Signed-off-by: dovics <wrs369@163.com>

Merge pull request casbin#521 from GopherJ/fix-unhandled-escapesymbol

fix: should remove escaped double quotes

fix: wrong locks (casbin#513)

fix: add AddGroupingPolicies, AddNamedGroupingPolicies, AddPolicies &…

… AddNamedPolicies to SyncedEnforcer (casbin#512)

Merge pull request casbin#510 from GopherJ/improve-locks

fix: remove unnecessary locks

fix: use map to store policy index (casbin#500)

* fix: use map to store policy index

* fix: add benchmark for add/remove policy

* fix: add RWMutex for Assertion

fix: Avoid typecast adapter to BatchAdapter for RemovePolicy (casbin#495

)

fix: Avoid typecast to BatchAdapter for RemovePolicy

feat: Support pattern function in 3rd args of g (casbin#475)

* feat: Support pattern function in 3rd args of g