v0.4.0 Smaller Index

Index Compression

Index compressed with zstd and is 60% smaller.
The index is no longer entirely read into memory, making large amount of file less of
a problem.

Ideally RAM usage used in indexing and searching will not exceed 150MiB,
however large the filesystem database is.
This does not include memory used by Qt and other GUI components, which may
use way above this value, especially when previewing multimedia.