Fix intermittent import failure for firmware 1.15C

[chackneyrules]

Fixes #6

Firmware 1.15C does not send a SysEx message for every pattern slot — it omits empty/unused patterns. The app expects all 128 DTPatternKitResponse messages, leaving any unoccupied slot as Nothing in the patterns bank. testAllThere then returns TestFail, which aborts the import entirely.

This change makes the missing-patterns check return TestWarn () instead of TestFail, consistent with how missing sounds are already handled. The import succeeds, the user sees a warning, and the empty pattern slots remain empty (which is correct — they were empty on the device).

missingSamples is intentionally left as TestFail since the sample pool arrives in a single ProjectSettings SysEx and can never be partially missing.

[mzero]

I don't have this OS version yet, so I can't check it... I'll review this when get a copy.

[mzero]

I have it on authority from Elektron that this is not a change in how SysEx works with 1.15C, and that all the patterns should be sent. If some aren't received, it isn't because they were empty, it is because of the on-going problems with OSes and Browsers handling SysEx > 64k bytes.

Therefore, I feel this patch is misleading in that some users will things have worked, but in fact they have not.