Fix buffer stomping; retool Makefile.

The Makefile is now useful for building ke(1) to aid in more rapid
development. This works because ke doesn't (yet) need any special
non-system libraries.

File.cc

@@ -64,10 +64,10 @@ OptOutFileStream File::Flush()
 			return std::nullopt;
 		}
 
-		return {new std::ofstream(this->path, this->mode|std::ios::trunc)};
+		return {new std::ofstream(this->path, std::ios::out|std::ios::trunc)};
 	}
 
-	return {new std::ofstream(this->path, this->mode)};
+	return {new std::ofstream(this->path, std::ios::out)};
 }
 
 
@@ -78,7 +78,7 @@ File::Refresh()
 		return std::nullopt;
 	}
 
-	return {new std::ifstream(this->path, this->mode)};
+	return {new std::ifstream(this->path, std::ios::in)};
 }