Minor refactoring: coding style and JavaScript new features
- VEXPController : do not use getters and setters inside VEXPController functions.
- ReciprocalView3D.drawLattice : redo the merge.
- Move the require of ag-grid and xtal in the local files. Warning: do not: require(...xtal.js) but require(...xtal).
- JS file names should contain - rather than _.
- Use camel case (spaceGroups) rather than snake case (space_groups).