C/C++/ObjC language server

 This originates from cquery, and is a server implementing
 Language Server Protocol for C/C++/Objective-C. It supports:
 .
  * code completion (with both signature help and snippets)
  * definition/references, and other cross references
  * cross reference extensions:
    $ccls/call $ccls/inheritance $ccls/member $ccls/vars ...
  * formatting
  * hierarchies:
    call (caller/callee) hierarchy, inheritance (base/derived) hierarchy,
    member hierarchy
  * symbol rename
  * document symbols and approximate search of workspace symbol
  * hover information
  * diagnostics and code actions (clang FixIts)
  * semantic highlighting and preprocessor skipped regions
  * semantic navigation:
    $ccls/navigate