enable sound filenames starting with /flash or /sd

Currently soundfiles for bl00mbox have always to be located in /flash. This MR changes this behavior and adds a check for paths starting with /flash/ or /sd/.

fixes #58 (closed)

Looks good, but you'll have to rebase this against current main.

added 4 commits

• 7b38f29f...feaf6d62 - 3 commits from branch flow3r:main
• 335a48a7 - Merge branch flow3r-firmware:main into main

Compare with previous version

@q3k: done!

merged