DefOtions definitions

with #11
```
@Define
  @DefOptions
    TexBeginEnd (name : String) = @Begin \begin{$name} @End \end{$name}
  @Environments
    Document = @TexBeginEnd "document"
```
otherwise syntax will be to verbose:
```
@Define
  @DefOptions
    TexBeginEnd (name : String) = "@Begin \"\\\\\\\\begin{$name}\" @End \"\\\\\\\\end{$name}\""
  @Environments
    Document = @TexBeginEnd "document"
```