find and grep: searching for files and lines

The ~/findlab/ directory is already filled: old and fresh logs, a "fat" binary file, an empty .tmp, and a couple of config files with notes.

Two commands cover almost all everyday searching:

• cmd-find searches for files by predicate (name, type, time, size).
• cmd-grep searches for lines inside files by regex.

Joining them through a pipe and xargs is usually faster than an IDE's built-in search: in one command you find every .conf file that mentions the parameter you need.