Fix mei encoding - precedes / follows issue

[timothydereuse]

Resolves: #1112

Makes a few changes to ensure that two custodes cannot appear in the same syllable (and does a little improvement to the local testing script to aid in debugging this issue).

The whole build_mei_file.py file is still a little long and unwieldy and should be broken up, but that should be fixed in its own PR.

[yinanazhou]

Also made changes for #1122

[yinanazhou]

@homework36 could you please follow up this PR?

[homework36]

@homework36 could you please follow up this PR?

The CI test cannot pass.
This line needs to be fixed but I'm not quite sure what to do: https://github.com/DDMAL/Rodan/blob/245db995bf09bef4521992d4146085b7918d2dfd/rodan-main/code/rodan/jobs/MEI_encoding/MEI_encoding.py#L147C1-L148C1

36/51: MEI Encoding ... 
FAILED
37/51: Diagonal Neume Slicing ... 
{'Slice Prioritization': 2, 'Minimum Segment Length': 5, 'Angle': 45, 'Minimum Glyph Size': 0, 'Maximum Recursive Cuts': 10, 'Minimum Slice Spread': 0.3, 'Low Valley Threshold': 1, 'Smoothing': 1}


FAIL: test_all_jobs (rodan.test.test_all_jobs.RodanJobsTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/code/Rodan/rodan/test/test_all_jobs.py", line 40, in test_all_jobs
    self.fail(f"{len(failed)} jobs out of {total} failed\n{failed_msg}")
AssertionError: 1 jobs out of 51 failed
======================
MEI Encoding <class 'rodan.jobs.MEI_encoding.MEI_encoding.MEI_encoding'>
======================
Traceback (most recent call last):
  File "/code/Rodan/rodan/test/test_all_jobs.py", line 29, in test_all_jobs
    task.test_my_task(self)
  File "/code/Rodan/rodan/jobs/MEI_encoding/MEI_encoding.py", line 147, in test_my_task
    testcase.assertEqual(gt_line, pred_line, "Line {}".format(i))
  File "/usr/local/lib/python3.7/unittest/case.py", line 852, in assertEqual
    assertion_func(first, second, msg=msg)
  File "/usr/local/lib/python3.7/unittest/case.py", line 1233, in assertMultiLineEqual
    self.fail(self._formatMessage(msg, standardMsg))
  File "/usr/local/lib/python3.7/unittest/case.py", line 693, in fail
    raise self.failureException(msg)
AssertionError: '<mei[24804 chars]lrx="4748" lry="2580" ulx="4735" uly="2546" xm[28406 chars]mei>' != '<mei[24804 chars]lrx="3113" lry="3078" ulx="3070" uly="2932" xm[28197 chars]mei>'
Diff is [208](https://github.com/DDMAL/Rodan/actions/runs/12164377858/job/33925886358?pr=1130#step:10:209)807 characters long. Set self.maxDiff to None to see it. : Line 1