Corrupt pbf files cause bugs

[mnm-matin]

partially downloaded/corrupt pbf files cause decoding errors in pbf files. it also seems like the update flag does not re-download the file

could solve this by implementing:

• fixing the update flag
• verification of pbf using hashes before extraction
• a clean arg in the argparser that deletes the pbf files.

[mnm-matin]

just bumping this myself.

[mnm-matin]

md5 should be downloaded together with the pbf file, and verification should be carried out. file should be delted if there is an md5 mismatch. commented out code is available in the code base that does basically this.