Moving additional bash functions into .bash_functions.
1. Assign a NTFS screens tmp folder for permission requirement (0700).
2. Add .bash_functions for bash configuration and other application
   environment configuration (like, screen).
3. Expand bash history from default (ex:500) commands to 4096 commands.

[Known issue]

There is no a remote server runs screen and its terminals.
If screen is detached (with all sub-screens runs a seperated terminal)
and the root terminal (like, first opened mintty) is closed, the mintty
will hang on logout.

The screen of cygwin is not as useful as the screen on remote unix/
linux server.