Fixes to gatan2 / SerialEM plugin

[Baharis]

This PR encapsulates several fixes performed by Jaedong Kang (@jdkang0810) from the Korea Advanced Institute of Science and Technology, who adapted current version of Instamatic to an FEI / Gatan Rio16 setup. The changes were reviewed, refactored, and mostly accepted by me. Text below comes from our e-mail exchange and was written by Jaedong and modified by me.

The changes were performed for Python 3.11+ while using SerialEMCCD/SEMCCD plugin(GMS 3.42) in DigitalMicrograph(DM 3.42.3048), leading to the following communication scheme: Instamatic → CameraGatan2 / GatanSocket → SerialEMCCD/SEMCCD plugin in DigitalMicrograph → Rio16.

Issues and changes

• On the 64-bit Python installation, numpy.int_ is 64-bit, whereas the Windows C long values expected by the SEMCCD socket protocol are 32-bit. This causes incorrect message lengths and errors such as Command wrong length: needed=16 numBytes=104. Thus, gatansocket3.py was modified to explicitly encode integers as 32-bit little-endian (<i4 / np.int32).
• DM/SEMCCD Port obtained from the environment variable is explicitly converted to an integer.
• Host can now be used instead of always forcing 127.0.0.1.
• Socket timeouts were added (controlled by a new SERIALEMCCD_TIMEOUT, 10 seconds by default).
• The connection can reconnect and retry once if a send operation fails, making communication considerably more stable;
• camera_gatan2.py was modified to favor a standard argument name binsize rather than binning, though both are accepted [@jdkang0810 was subtle about it, but I added an explicit warning that use of binning is deprecated!].
• The image dimensions and ROI sent to the SEMCCD plugin are now dynamically adjusted for binning – no need to calculate them manually in the config file, as was required before.
• The corrections argument used for image acquisition was changed from 0 to -1, allowing DM to use Rio16's own default settings instead of disabling them.
• The image-transfer code in gatansocket3.py was modified to receive images into a 1D bytearray first, followed by conversion to a uint16 NumPy array, making transfer more robust, particularly for the current Python version and larger Rio16 images.
• [A naive implementation of get_movie was added to camera_gatan2.py to better integrate it with new code - Daniel]

[Baharis]

@jdkang0810 This PR only concerns changes to the gatan2 camera; I'm still thinking if and how introduce the others. I modified your code quite a bit to match code style, also I'm annoying like that and like short lines and f'{this=}' syntax. I moved some comments to doctrings. I also decided not to add type checks inside gatansocket3.py (it is a low-level object and these should be already checked earlier) and hard-coded binning assertion in {1, 2, 4}. Other than that, IMO this is a great fix that might have otherwise been an issue for others attempting to connect a Rio camera.

Judging by the state of this code, I doubt we have any active developers relying on gatansocket3.py / camera_gatan2.py, but just in case I will let this PR sit for a few days in case anyone has any comments.