Use different build include paths.
Change the Lock interface.
Add a threadsafe doubly linked list.
Extend ConcurrentList with size and optional locks.
Add Lock::tryLock()
Remove namespace std from utils/File.cpp
Add a logging utility.
Add a Mutex implementation in addition to locks.
Add ConcurrentList::tryLock.
Move PageId to the right namespace and update tests.
Update the BufferFrame.

 - Implement load() and save().
 - Add tryLock() to find unlocked frames.
 - Add public methods to change the data pointer.
 - Add a "move"-ish constructor to take over another frame.
Implement the BufferManager correctly.
Add a buffertest executable.