See https://github.com/turt2live/matrix-media-repo/issues/353

This reverts commit 5e51abbd.

For https://github.com/turt2live/matrix-media-repo/issues/53

This is probably super ugly Go code, but it works.

Fixes https://github.com/turt2live/matrix-media-repo/issues/312

Fixes https://github.com/turt2live/matrix-media-repo/issues/311

Fixes https://github.com/turt2live/matrix-media-repo/issues/276

Fixes https://github.com/turt2live/matrix-media-repo/issues/274
Fixes https://github.com/turt2live/matrix-media-repo/issues/273

Fixes https://github.com/turt2live/matrix-media-repo/issues/275

Fixes https://github.com/turt2live/matrix-media-repo/issues/299

Fixes https://github.com/turt2live/matrix-media-repo/issues/296
Fixes https://github.com/turt2live/matrix-media-repo/issues/277

Fixes https://github.com/turt2live/matrix-media-repo/issues/271 at the same time

Instead of buffering all the export files into memory (which could be hundreds of gb) we buffer them in one at a time and hope that they don't contain extra information.

On a 171mb export, this change used 45mb of memory at most. Previously the task would have required about 1gb. For larger (200gb+ exports) this is obviously better.

Fixes https://github.com/turt2live/matrix-media-repo/issues/146

Fixes https://github.com/turt2live/matrix-media-repo/issues/233

Fixes https://github.com/turt2live/matrix-media-repo/issues/49

Fixes https://github.com/turt2live/matrix-media-repo/issues/268

Fixes https://github.com/turt2live/matrix-media-repo/issues/265

Also fixes an issue with apng thumbnails being cropped in multiplying ways.

In various places in the code base, the address and port are joined using a `:`.
This causes issues with IPv6-addresses (see #247).
Address this by using net.JoinHostPort everywhere.

Signed-off-by: Silke Hofstra <silke@slxh.eu>

Resolves #244

Signed-off-by: Silke Hofstra <silke@slxh.eu>

This removes a select across the whole table by ensuring we generate a media ID which is highly unlikely to conflict with the database.