Concurrency: add initial versioning for search operation
Refactoring: extract method
Concurrency: initial versioning for insert
Concurrency: add right link to InnerEntry
Concurrency: search in right entries if there was split
Fix compilation
Hack: covariant cast
Fix compilation
Add test for basic inserting into Gist
Fix compilation: drop const?
Support adding data to LeafEntry
Add basic tests
refactoring
insert is back
Fix seg fault
Fix compilation: take LeafEntry as argument and cast it to Entry
Add locks for search and insert
Add simple tests for insertion
Merge pull request #9 from zarechenskiy/master

Compilation fix, basic concurrency