Improvements, optimisations and changes to exp scripts

- Script exp-results-histparams massively improved and optimised by a
factor of 25x. It now computes standard deviation as well as mean
values, and compiles a long calculation string to pass to bashcalc
rather than invoking it repeatedly. Some added error checking
- Exp-results also improved, and adjusted to summarise the standard
deviation values
- Compile script now checks if source files have changed since last
compile (similar to Makefiles)
- Added exp-non-hist for running experiments of all non-hist nodes in
one go (since this is much more straightforward than running hist nodes
with params files)
- Indentation and formatting fixed in a couple of the other scripts