minor improvements

JSX/JNPM implementation
new options jnpm.kson config:

• transformFunction (defaults to "React.createElement"). Enables use of jsx for other libs than react
• nodeLibraryMap. Globally patch require/imports to a distinct package. (e.g. patch react to preact)

general interop with non java via json

• improved Unknown implementation. A javascript client might send arbitrary json (without the need to adapt to java-object-serialization requirements), the server side java method then receives an Unknown object reflecting the json structure (see also doc+samples)