need more information about unknown bindings

[jurgenvinju]

if (binding == null) {
			return makeBinding("UNKNOWN1", null, null);
}

This is from BindingsResolver but we need to know what AST node this is about to be able to debug it, or the source location of the AST node we are processing at the moment.

[jurgenvinju]

Examples we ran into during parsing of subversion:

typedef svn_boolean_t (*filter_func_t)(const char *key);
here, *key is recognized as UNKNOWN1
static svn_error_t *filter_dir_changed(const struct svn_diff_tree_processor_t *processor, ...)
here, const struct svn_diff_tree_processor_t *processor is unknown
SVN_ERR(svn_io_remove_dir2(wc_path, TRUE, NULL, NULL, pool));
for this example, NULL is unknown

Especially when resolving the entire project it is very hard to debug these issues. If we add more diagnostics first, maybe solving each issue will be easier, but also the user of clair will be better informed and can make workarounds.