Fix compatibility with vle1.1:

- Compatibility with vle 1.1.
- Fix bug fixes for the Rvle class API.
- Complex data are now converted between vle and R.
- Experiment plan can be expressed into data frames (setting 'inputs').
Replace old vle.conf

- replace old vle.conf of VLE_HOME
- avoid warning by using normalizePath
Fix coding style and DESCRIPTION file

- DESCRIPTION file is reset.
- Coding style is modified.
- Some useless comments are removed.
Fix rvle initialization

- Initialization vle::Init is required to be a global object.
- Use .onLoad, .onUnload functions rather than deprecated .First.Lib
- Remove useless library(rvle) into tests