Add .gitignore
Remove the dependence from csh.

The `pcxarch` have been modified for running into bash.

The shell scripts have been renamed by append `.sh` so that the
user easy know that it wasn't a binary file.
Resolve the problem of multiple definition of `main`.

Add `-z muldefs` is just a fast and ugly solution for the problem.
Start DOC
Copy some information from PCx User Guide to Documentation
Add information for debug