Moved CPrimaryScreen and CSecondaryScreen to the lib/synergy

and the platform specific implementations to lib/platform.
Added an lib/arch method to query the platform's native wide
character encoding and changed CUnicode to use it.  All
platform dependent code is now in lib/arch, lib/platform,
and the programs under cmd.  Also added more documentation.

lib/arch/CArch.cpp

@@ -130,6 +130,8 @@ CArch::~CArch()
 CArch*
 CArch::getInstance()
 {
+	assert(s_instance != NULL);
+
 	return s_instance;
 }
 
@@ -569,6 +571,12 @@ CArch::convWCToMB(char* dst, wchar_t src, CArchMBState state)
 	return m_string->convWCToMB(dst, src, state);
 }
 
+IArchString::EWideCharEncoding
+CArch::getWideCharEncoding()
+{
+	return m_string->getWideCharEncoding();
+}
+
 double
 CArch::time()
 {