SC13: Various kinds of include file.

1. Include file is empty.
Before include
@i sc13a
After include

2. Include file contains a single blank line.
Before include
@i sc13b
After include

3. Include file contains two blank lines.
Before include
@i sc13c
After include

4. Include file contains a single line with text on it.
Before include
@i sc13d
After include

5. Include file's last line is not properly terminated.
Before include
@i sc13e
After include

6. Include file is ordinary.
Before include
@i sc13f
After include

7. Test upper case I and file extension inheritance.
Before include
@I sc13f
After include

End of test File.