[feature] Rebuild btree by scanning leaf pages. Main step towards simplified recovery.
Rebuilding btree from leaf pages works now.
[ignore]  Btree code cleanup
[feature] Simplify transaction log: after a crash, the btree for dom.dbx and collections.dbx is now rebuild from the leaf pages. We thus no longer need to keep track of operations on branch pages, resulting in a more robust recovery process.
[ignore]  cleanup recovery log messages
[ignore] Recovery: call sync after repair
refactor configurator
Merge branch 'feature/recovery' of https://github.com/wolfgangmm/exist into feature/recovery
Merge branch 'develop' into feature/recovery
Merge branch 'develop' into feature/recovery
Merge branch 'develop' into feature/recovery
Merge pull request #112 from dizzzz/develop

Adding comments to understand the class. Required to do some refactoring...
Merge branch 'develop' into feature/recovery
Merge branch 'feature/recovery' into develop
Merge pull request #113 from wolfgangmm/develop

Merge crash recovery branch