Support on default templates of IntelliJ annotations

[Zardoz89]

https://www.jetbrains.com/help/idea/template-data-languages.html#special-comments

Comment	Description
@Implicitly included	Any FreeMarker file that starts with this comment is included into all files that are in the same module or its dependencies. Use such a dedicated comments file to define IDE-specific comments, so that they do not pollute your template files.
@ftlvariable	Defines a variable. For example, the following comment declares a variable named foo of type String, visible only in the specified file: <#-- @ftlvariable name="foo" type="java.lang.String" file="path/to/file" -->
@ftlroot	Defines the path relative to which import and include directives are resolved. The path is specified relative to any of the directories in the current FTL file's package. Paths inside JARs are also supported, for example: <#-- @ftlroot "path/to.jar!/path/inside/jar" -->

[Zardoz89]

Issue #9 it's required to handle this.