D Language Server

This is still a work in progress; there might still be bugs and crashes. DLS implements the server side of the Language Server Protocol (LSP) for the D programming language. It doesn't do much itself (yet), and rather uses already available components, and provides an interface to work with the LSP. DLS is usable using FreeBSD's Linux binary compatibility system (tested on FreeBSD 12.0-RELEASE). Code completion, going to the symbol definition, finding references, symbol renaming. Error checking, code formatting (document, range and on-type), symbol listing (current document and workspace-wide). Symbol highlighting, documentation on hover, random, frustrating crashes.