Tidy up source code

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Use methods for naming EOLs and Encoding to avoid different names

Note that the object file for libsvn_diff/eol.c needs to be specified to another name to avoid collision with EOL.cpp

Based on TortoiseSVN revision 24309

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Use empty()/IsEmpty() when possible instead of size(), GetLength() or empty string

Use angle bracket for system header

Based on TortoiseSVN revision 24312, 24313

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>