Revert "(PyScriptEngine) Load the site module automatically"

This reverts commit a14100bdfb2ce9a7ac18d5bc91b9d99a384218bf.
This operation is now done in the Jython implementation directly
Revert the import of site in PythonScriptingConsole

Now done automatically in the Jython implementation.
Remove the call to JythonLibsManager to extract the Python scripts.

Now done in the Python Extractor plugin, which is independant of the
Script-Editor (allows uses of Python outside the Script-Editor !)
Remove unused import
Revert "(ScriptEngine) Rename 'evalFile' to 'execFile' since nothing is evaluated, strictly speaking"

This reverts commit 5f902ed38956f4b9c0892a6597ac8111499ef1f2.

I know understand that this corresponds to JSR 223.
Revert "(ScriptEngine) Rename 'eval' to 'exec' since nothing is evaluated, strictly speaking"

This reverts commit 3afca6dc094fe91da592579ea78aa970745ac09c.

I know understand that it corresponds to JSR 223.