The struct entry 'extension' is not really a (filename) extension, but
rather a unique ID used for input or output formats, e.g. in the sigrok
CLI or GUI interface. Thus, rename it accordingly.
This is the file format for the OpenBench Logic Sniffer "Alternative" client.
Details: https://github.com/jawi/ols/wiki/OLS-data-file-format
This is work-in-progress.
Currently the number of samples is hardcoded to 10000. Also, this will
require a real logic analyzer as input at the moment, and will not yet
work with the "demo" driver.