Always keep stdout with -e

The idea being that this is as close to just running the function as possible.
Update documentation with notes on -e
Merge branch 'exec'
Fix minor issues in -h output
Fix failing test

Line number changed after merge - hadn't checked until now.
Stop testing csh as it cannot be supported

Unfortunately csh does not support the definition of functions, meaning ts
cannot be run in csh unless it is re-written as individual scripts... and maybe
not even then.