Need `using TimerOutputs` in Main - JLD seems to be flaky when called from within a module

[johnomotani]

At present it seems to be necessary to call using TimerOutputs in Main (i.e. the REPL, or a script that uses TimerOutputComparisons), in addition to using TimerOutputComparisons.

This may be related to JuliaIO/JLD.jl#252 - to try and work around that issue we export JLD (which maybe will be unnecessary if/when that issue is fixed). However export TimerOutputs or export TimerOutput did not seem to help.