Add a normal README.md

Add functions to make prompt customization easier, like bash PS1 format codes

Add command operator<(command, command_line_functor);

Add command to fd conversion, for using commands as files, see https://www.gnu.org/software/coreutils/manual/coreutils.html#tee-invocation

Add command operator<(command, int fd); and same for <, >>, >=, >>=

Add wildcard selection

Make shell prompt customizable

Catch signals in cling to behave like bash

Change shell prompt from cling to ccsh, use # for root shell

Add ccsh::source for sourcing commands

Add a flag to command_base to run command in the dtor.

Fix output redirection permission issue.

Improve type safety via boost::filesystem (later std::filesystem) and operator""_p

Invent a fancy syntax for command switches. Giving them as strings (e.g. ccsh::ls("-lah")) lacks static checking and type safety.

The same goes for argument pairs like cssh::gcc("...", "-o", "file.o")

Add operator< for input redirection

Add operator>= for error redirection

Add operator>> for output appending

Add operator>>= for error appending

Add operator|| and operator&&

Add command operator>(command, std::vector<std::string>&); and same for <, >>, >=, >>=

Add command operator>(command, std::string&); and same for <, >>, >=, >>=

Add command operator>(command, command_raw_functor); and same for <, >=

Add command operator>(command, command_line_functor); and same for >=