This is a clone of #740, but without the amtl ke::AString lowercase which was implemented in a new version of amtl that 1.9-dev isn't pinned to. Updating this pin and moving fixes is beyond what should go in 1.9, and this fixes a annoying and user-impactful bug with reload/unloading plugins on windows.
Currently in 1.9, once a plugin is loaded into the pluginsys, they must be used with lowercase characters *only*, since pr #709 ignorantly modified their names.
```
// test.smx exists in /plugins/
sm plugins load TEST.smx // successful
sm plugins unload TEST.smx // TEST.smx not found, it's actually test.smx
```
This pr fixes that error by converting *all* lookups, not just loads.
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