syntax: Highlight dots in aliases as aliases

It's confusing that "defmodule Foo.Bar" was highlighted differently than
"Foo.Bar.fun". Unify the two.

spec/syntax/alias_spec.rb

@@ -4,9 +4,10 @@
 
 describe 'Alias syntax' do
   it 'colorize only module alias' do
-    expect(<<~EOF).to include_elixir_syntax('elixirAlias', 'Enum')
-      Enum.empty?(...)
-    EOF
+    str = "Enum.empty?(...)"
+    expect(str).to include_elixir_syntax('elixirAlias', 'Enum')
+    expect(str).to include_elixir_syntax('elixirOperator', '\.')
+    expect(str).to include_elixir_syntax('elixirId', 'empty?')
   end
 
   it 'colorize the module alias even if it starts with `!`' do
@@ -33,4 +34,15 @@
     expect(str).to include_elixir_syntax('elixirAlias', '3')
     expect(str).to include_elixir_syntax('elixirAlias', 'Manager')
   end
+
+  it 'colorize dots in module alias' do
+    str = "Foo.Bar.Baz.fun(...)"
+    expect(str).to include_elixir_syntax('elixirAlias', 'Foo')
+    expect(str).to include_elixir_syntax('elixirAlias', '\.\(Bar\)\@=')
+    expect(str).to include_elixir_syntax('elixirAlias', 'Bar')
+    expect(str).to include_elixir_syntax('elixirAlias', '\.\(Baz\)\@=')
+    expect(str).to include_elixir_syntax('elixirAlias', 'Baz')
+    expect(str).to include_elixir_syntax('elixirOperator', '\.\(fun\)\@=')
+    expect(str).to include_elixir_syntax('elixirId', 'fun')
+  end
 end

spec/syntax/defmodule_spec.rb

@@ -10,9 +10,10 @@
   end
 
   it 'defines module name as elixirModuleDeclaration' do
-    expect(<<~EOF).to include_elixir_syntax('elixirModuleDeclaration', 'HelloPhoenix.HelloController')
-      defmodule HelloPhoenix.HelloController do
-    EOF
+    str = "defmodule HelloPhoenix.HelloController do"
+    expect(str).to include_elixir_syntax('elixirModuleDeclaration', 'HelloPhoenix')
+    expect(str).to include_elixir_syntax('elixirModuleDeclaration', '\.')
+    expect(str).to include_elixir_syntax('elixirModuleDeclaration', 'HelloController')
   end
 
   it 'does not define module name as elixirAlias' do

syntax/elixir.vim

@@ -39,7 +39,7 @@ syn match   elixirOperator '\.\.\|\.'
 syn match   elixirOperator "\^\^\^\|\^"
 syn match   elixirOperator '\\\\\|::\|\*\|/\|\~\~\~\|@'
 
-syn match   elixirAlias '\([a-z]\)\@<![A-Z]\w*'
+syn match   elixirAlias '\([a-z]\)\@<![A-Z]\w*\%(\.[A-Z]\w*\)*'
 
 syn match   elixirAtom '\(:\)\@<!:\%([a-zA-Z_]\w*\%([?!]\|=[>=]\@!\)\?\|<>\|===\?\|>=\?\|<=\?\)'
 syn match   elixirAtom '\(:\)\@<!:\%(<=>\|&&\?\|%\(()\|\[\]\|{}\)\|++\?\|--\?\|||\?\|!\|//\|[%&`/|]\)'