Revert "Fix highlight for atoms containing @ character"

This reverts commit eb06df6.

Author: jbodah

spec/syntax/atom_spec.rb

@@ -88,19 +88,4 @@ def project do
  end
  EOF
  end
-
- it 'detects atoms containing @ in it' do
- expect(<<~EOF).to include_elixir_syntax('elixirAtom', '@somewhere')
- :atom@somewhere
- EOF
- expect(<<~EOF).to include_elixir_syntax('elixirAtom', '@somewhere')
- [atom@somewhere: nil]
- EOF
- end
-
- it 'detects atoms containing Unicode letters in it' do
- expect(<<~EOF).to include_elixir_syntax('elixirAtom', 'ó')
- :atóm
- EOF
- end
 end

syntax/elixir.vim

@@ -41,9 +41,9 @@ syn match elixirOperator '\\\\\|::\|\*\|/\|\~\~\~\|@'
 
 syn match elixirAlias '\([a-z]\)\@<![A-Z]\w*\%(\.[A-Z]\w*\)*'
 
-syn match elixirAtom '\(:\)\@<!:\%([a-zA-Z_]\%(\w\|@\|\P\)*\%([?!]\|=[>=]\@!\)\?\|<>\|===\?\|>=\?\|<=\?\)'
+syn match elixirAtom '\(:\)\@<!:\%([a-zA-Z_]\w*\%([?!]\|=[>=]\@!\)\?\|<>\|===\?\|>=\?\|<=\?\)'
 syn match elixirAtom '\(:\)\@<!:\%(<=>\|&&\?\|%\(()\|\[\]\|{}\)\|++\?\|--\?\|||\?\|!\|//\|[%&`/|]\)'
-syn match elixirAtom "\%([a-zA-Z_]\%(\w\|@\|\P\)*[?!]\?\):\(:\)\@!"
+syn match elixirAtom "\%([a-zA-Z_]\w*[?!]\?\):\(:\)\@!"
 
 syn keyword elixirBoolean true false nil