Version 0.7a Released

Squirrel Shell 0.7a released.
Changes:
- In Windows tilde as the first character in path is replaced with current user's directory ("c:\Documents and Settings\*" in WinNT).
- Added strchar() function.
- Added substr() function.
- Added filepath() function.
- Added filename() function.
- Added fileext() function.
- Written documentation.