super basic 'ls' and 'cat' for reading sqlfs files without mounting them

* both only take a single file arg
* 'ls' only shows the file names
* both currently only work with unencrypted sqlfs.db files
switch sqlfscat to use fwrite() and FILE *stdout for clarity
sqlfscat: get password from stdin for opening encrypted db file
sqlfsls: get password from stdin for opening encrypted db file
fuse_sqlfs: add example for how to open a file with a password