Adding basic support for Windows viewer. Using JAVA_HOME environment variable in Windows for checking correct Java configuration.
Checking that WindowsViewer is only loaded on Windows platforms
Fix indentation errors and pep8
pep8
win32 compat, pep8 and pep20

Fix java check (pep20):
- Always directly validate your indent (calling java)
- Don't validate transitives (which java, JAVA_HOME)
- If you can be explicit (java -version)

Don't open a command shell window if it gives no benefit
(creationflags).