Waste space and datatypes

[LinuxRocks2000]

The JSON files have quite a lot of wasted space (many superfluous whitespaces and newlines). Compressing them would be a significant improvement.
The numerical fields (ids) are all strings - this is also wasteful when loading into a compact memory format (like serde does in Rust) because it requires as much as 6 bytes when 2 would suffice - multiplied by thousands of entries.