Move to deployments → media → observation hierarchy

[peterdesmet]

This PR is a first step at updating the Camtrap DP structure, discussed in #203 (comment). It creates a linear hierarchy:

deployments → media → observations

It does so by:

• Removing the potentially conflicting foreign key deploymentID from observations (join should be made via media)
• Removing the redundant field timestamp from observations (info can be obtained from media)
• Removing mediaID from observations. Note that this currently restricts Camtrap DP to event-based observations only, but that will be resolved in a next update where we rename observations to event-observations and add a media-observations table.
• Updating the definitions of the media and observations table
• Renaming sequenceID to eventID in both the media and observation table
• Renaming sequenceInterval to eventInterval in the profile
• Renaming the controlled value sequence to event in classificationLevel in the profile
• Renaming sequence to event in definitions where relevant. The only occurrence is now in media.eventID:

Unique identifier of the event the media file belongs to. Events contain one or more media files (e.g. a single image or video or a sequence of successive images or videos) and are defined by package.project.eventInterval.

• Updating the example dataset accordingly
• Minor (unrelated) change to homepage and adding sitemap

The PR bumps the version from 0.5 to 0.6.

[peterdesmet]

Rather than merging this to main, I have created a 0.6 branch, that will include all upcoming changes for the release candidate.