fix(DefinitionResolver): find variables in sibling children (felixfbe… …cker#568) Fixes felixfbecker#566

fix(DefinitionResolver): don't crash if foreach key isn't a variable (f… …elixfbecker#564)

fix(DefinitionResolver): fix crash on unknown foreach type (felixfbec… …ker#562) Fix when unknown type is found in foreach expression

docs(used-by): mention Atom's ide-php in README (felixfbecker#559) adds Atom's ide-php package to "used by" section in README

feat: Signature help (felixfbecker#547) closes felixfbecker#18

ci(macos): try alternative method to download composer 

fix(diagnostics): update checking of $this usage to only error in sta… …tic methods (felixfbecker#545)

feat(diagnostics): report error when $this is used in a static method… … or outside a class method (felixfbecker#528)

fix(indexing): properly resolve self, static and parent keywords (fel… …ixfbecker#532) Previously we would dump static, self and parent as literal FQNs into the index.

fix(completion): don't suggest <?php on > characer (felixfbecker#527) closes felixfbecker#372