Xobjects

**Changes:**
- Add `__repr__` method to `HybridClass`

**Changes:**
- Allow pickle of `Struct` and `HybridClass` objects.

**Full Changelog**: https://github.com/xsuite/xobjects/compare/v0.2.4...v0.2.5

**Changes:**
- Enable OpenMP support.

**Full Changelog**: https://github.com/xsuite/xobjects/compare/v0.2.3...v0.2.4

**Changes**
- Fix (caching of compiled kernels).

**Changes:**
- Introduce possibility of disabling all Xsuite printed output (xtrack._print.suppress = True).
- Fix in type hints.

**Full Changelog**: https://github.com/xsuite/xobjects/compare/v0.2.0...v0.2.2

**Changes:**
- Fix in kernels_from_file.

**Full Changelog**: https://github.com/xsuite/xobjects/compare/v0.2.0...v0.2.1