Get rid of transaction_ledger_experimental.cpp

[drltc]

If the functionality in libraries/wallet/transaction_ledger_experimental.cpp is currently being used, then that source file should either be merged into transaction_ledger.cpp, or a more descriptively named source file.

If the functionality is not currently being used or not ready to be merged, that source file should be maintained in a separate branch and deleted from mainline until it is more finished.

[vikramrajkumar]

This is a non-issue. The code is work-in-progress as part of #845. Some of the code runs in parallel with the original transaction scanning code on the testnets for easier testing and development, and when it is ready, the code will run in parallel for some time on the real chain before replacing the old scanner.

It could be moved into a separate branch but I see no benefit other than a slightly cleaner mainline repository for a period of time until it is merged back in. There is plenty of other shelved/placeholder code throughout the codebase--it's not worth cleaning out at this point in time.