wmake: Add support for compiler type default rules
which may be optionally overridden by version-specific rules. For example the default rules for gcc on GNU/Linux x86_64 are in the wmake/rules/linux64Gcc directory. If there is a need to change any of the rules for a specific version of gcc, e.g. gcc-4.8.4 the directory wmake/rules/linux64Gcc48 may be created into which any of the language files may be provided containing the rules to override the defaults.