Nexus version

When opening a file which does not have a "NX version" attribute, the default behavior is to take the latest (1.1) version.

This seems counter-intuitive, as files having this "NX version" attribute will usually be written with recent software (>= 0.6), and files not having the attribute are likely to be written with older versions.
So unless I'm missing something, a more logical behavior would be to take 1.0 by default.

In any case, we should be able to choose the the NX version in HDF5TomoScan. Currently we have

class HDF5Tomoscan(...):
    # ...
    @property
    def nexus_version(self):
        return self._get_generic_key(
            "_nexus_version", self._NEXUS_VERSION_PATH, is_attribute=True
        )

    @nexus_version.setter
    def nexus_version(self, version):
        if not isinstance(version, float):
            raise TypeError("version expect to be a float")
        self._nexus_version = version

    @property
    def nexus_path(self) -> _NEXUS_PATHS:
        if self._nexus_paths is None:
            self._nexus_paths = get_nexus_paths(self.nexus_version)
        return self._nexus_paths

    @property
    def source_name(self):
        return self._get_generic_key("_source_name", self.nexus_path.SOURCE_NAME)

which means that the _nexus_version (and consequently _nexus_paths) cannot be chosen, as the nexus_paths is set at initialization.

scan = HDF5TomoScan(...)
print(scan.nexus_path) # _NEXUS_PATHS_V_1_1
scan.nx_version = 1.0 # too late, _nexus_paths is already set at this point!
print(scan.nexus_path) # Still returns _NEXUS_PATHS_V_1_1