- Obsoleted Command::exectute 'commandLine' argument. It is worse
than unnecessary, it is an uncategorized raw argument string, which
is only really useful for the 'execute' command, which itself now
calls Arguments::combine to reconstruct the command line string.
- Added en-US.h, which will be a header file full of string defines.
- Added logic to i18n.h to include en-US.h based on cmake command
line argument (cmake ... -DPACKAGE_LANGUAGE=1).
- Added one sample string.
