Strip invalid char data from strings on save

[hahn-kev]

relates to #328

I didn't see anything stripping out data, so I've gone ahead and done that via a compiled regex.

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LCM Tests

    16 files  ± 0      16 suites  ±0   2m 52s ⏱️ -2s
 2 846 tests +12   2 826 ✅ +12   20 💤 ±0  0 ❌ ±0 
11 332 runs  +48  11 164 ✅ +48  168 💤 ±0  0 ❌ ±0 

Results for commit cbd23aa. ± Comparison against base commit 0eb28b5.

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[jasonleenaylor]

Reviewed 4 of 4 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @hahn-kev)

[hahn-kev]

@jasonleenaylor I've added a link to a Wikipedia page documenting valid xml chars. One thing it mentioned is that U+10000–U+10FFFF is also valid, we have not included that here. Is that ok? or do we need to include it? I realized this has the potential to strip valid data on save if we get this wrong. So it might be worth a bit more checking to ensure this is correct otherwise users could start losing data on save without noticing right away.

[jasonleenaylor]

Sorry that I didn't see your comment before, yes we should include that range. It is very likely someone using FieldWorks will have a character in that range.

[hahn-kev]

@jasonleenaylor I worked with Martin H and rewrote the regex to just match the invalid characters that we want to remove, and he helped me come up with a test case which was outside the normal range.