Fix issues with virus scanners and non-english default encodings

CHANGED: Support non-English encodings by forcing UTF-8 support when accessing configuration files
CHANGED: Check for access to parent folder and for read permission to the config file before opening the file for reading (prevents issues with virus scanners)

Note: Implementation of both changes is loosely based on the mechanics of the MinecraftForge Configuration class. I'd suggest checking this for future reference.

The canRead() check does much of the magic, this prompts the virus scanner to scan the file, so it does not need to reject the request to fetch a file descriptor when actually trying to open the file.