File class members are encapsulated, and internal lock was added.

A lock was added to the file class to properly handle multiple threads accessing the self encryptor. Actual chunk storage and incrementing is still a work in progress.

This technically completes JIRA ticket MAID-153 too.
I concur with the analysis.

I also prefer the copying solution. I suggest that we handle this as a separate task though, and accept the current solution as-is.