Release 2.6.0. Added NEWS.md

Require BLACS 2.7.0 for remote devices and deserialised transition_to…

…_manual.

Bumped minor version for release

Merged in pstarkey/updated-labscript-version-requirement-an-154759647…

…8971 (pull request labscript-suite#58)

Updated labscript version requirement and bumped `__version__` for release

Merged in cbillington/labscript_devices/arbitrary_subfolders (pull re…

…quest labscript-suite#51)

Arbitrary subfolders for device code within labscript_devices