While most Unix-like systems use 16-bit user IDs,
Linux supports 32-bit UIDs since version 2.6.
UIDs above 65535 are used for UID namespacing of containers,
where a container has its own set of 16-bit user IDs.
Processes in such containers will have (much) larger UIDs than 65535.
Because the current format strings for `ST_UID` and `USER`
are `%5d` and `%9d` respectively, processes with such UIDs
lead to misaligned columns.
Dynamically scale the `ST_UID` column and increase the size of `USER`
to 10 characters (length of UINT32_MAX) to ensure that the user ID always fits.
Additionally: clean up how the titlebuffer size calculation and ensure
the PID column has a minimum size of 5.
Nathan Scott