This change drops the overhead of capturing the process output. The
io module in Python is similar to the POSIX API for a file read
where a read will return up to the buffer size rather than blocking
until the buffer is full.
The conversion to Python3 added an eval() call which is wrong.
Fix the spelling in execute.
Fix labels in the tester gdb locking.
Check the debug-trace arguments.
Close#2642.
Installing PYO and PYC does not work so disable this. Move the
Python check to the top level and have a single place.
Fix the install paths a revert the 'from . import' changes. This
is resolved by installing into the correct paths.
