update bin/README
tools: use cabal builds for profiling
tools: benchmarking updates
tools: fancy .ghci for hledger-web

Some configuration for running hledger-web in ghci, and misc. utilities
including hlint/hoogle/hayoo and a not-yet-working yesod devel-like
reloader from a recent reddit thread. (If enabling these, also uncomment
the required libs in hledger-web.cabal). Although it's not yet
automated, we can now test hledger-web changes without relinking:

>>> :serve
Starting web app on port 3000 with base url http://localhost:3000
Press ctrl-c to quit
  C-c C-cInterrupted.
>>> :r
Ok, modules loaded: Settings, Main, Hledger.Web.Main, Application, Hledger.Web.Options, Settings.Development, Import, Handler.RootR, Handler.JournalR, Handler.RegisterR, Handler.SidebarR, Handler.Common, Handler.Utils, Foundation, Settings.StaticFiles, Handler.Post.
>>> :serve
Starting web app on port 3000 with base url http://localhost:3000
tools: make repl[lib,web], cabal repl in each package