feat(API wrapper): separates implementation from public API

* moves implementation to impl subdirectory
* adds prefix _impl to implementation symbols
* removes double compilation for shared and static libraries
* fixes include guards
* fixes usage of extern "C"

include/wsfs/core/status.h

@@ -0,0 +1,17 @@
+#ifndef WSFS_STATUS_H
+#define WSFS_STATUS_H
+
+#define WSFS_GOOD 0
+#define WSFS_BAD  1
+
+#define WSFS_BAD_NOTIMPLEMENTED 2
+#define WSFS_BAD_TIMEOUT        3
+#define WSFS_BAD_BUSY           4
+#define WSFS_BAD_FORMAT         5
+
+#define WSFS_BAD_NOENTRY 101
+#define WSFS_BAD_NOACCESS 102
+
+typedef int wsfs_status;
+
+#endif