Fix: merge must fail when trying to create 2 nodes with same id but different labels (e.g., MERGE (a: Foo)-[r:KNOWS]->(a: Bar))
Merge pull request #2317 from davidegrohmann/2.0-maint

Fix: merge must fail when trying to create 2 nodes with same id but different labels
Add SKIP and LIMIT to the QueryGraph
Make Ronja plan SKIP and LIMIT together with ORDER BY
Don't assume order in Cypher result of Meal docstest.
Catch any exception coming out of trying to sample this value. If it fails it's ok. No worries. Better luck next time, and all that.
Add Cost and Cardinality for SORT, SKIP and LIMIT
Add new pipes

o Add LimitPipe, SkipPipe and a new SortPipe
o Rename the old SortPipe to LegacySortPipe
Let projection be done before sorting

When sorting, a row needs to be compared with other
rows quickly and multiple times. To facilitate this,
force projection to happen, so sorting doesn't have
to execute an expression for every comparison.
Use default keep-logical-logs (7days)
Merge pull request #2324 from systay/ronja-slice

SKIP and LIMIT for Ronja
Tagging for version 2.1.0-M02
Back to development version.
Fixes race that can cause duplicate writes in XaLogicalLog

There is a possible window where a transaction may fail to flush
 the log buffer (for example, during a commit) and even though
 it will set the KernelHealth to notOk, another thread can still
 come and try to flush the same contents again (say, by attempting
 a commit of its own tx). This can cause the log to be unrecoverable.
 This commit fixes this issue by introducing checks to KernelHealth
 before any write happens to the log's underlying file.
Store resolved ids for label, property names, and rel types in semantic table rather than ast
Sort files to make it easier to find the correct files in the log. Specifically, it should be easy to see what logical logs are available, and what sizes they have. Without this it's pretty darn hard.
Merge pull request #2326 from digitalstain/1.9-fix-damaged-log-writes

Fixes race that can cause duplicate writes in XaLogicalLog
added script to detect unauthorized contributors
Make Cypher reject using the same relationship identifier for multiple pattern
added script to detect unauthorized contributors