Production-like building

[kpp]

There are no checks for dependencies in CMake:

• libreadline
• libtinfo
• threads
• llvm-config (program)
• the whole llvm package (headers+libs)

Also we should add proper --help, --version to make llst work with help2man (help2man ./llst | nroff -man | less):

• add --version

We need to:

• add optional building of man pages in CMake
• find pod2man
• find gzip

Also we have to add a must-have target to CMake:

• target uninstall