Rework pkg/log, add 'loglevel' and 'logdate' flags, streamline

- removes some previously added manual location strings: now handled by pkg/log depending on loglevel
- kept manual string locations on fmt print functions
- add 'notice' and 'critical' loglevels
- add 'Panic' and 'Panicf' functions to log panics
- adresses issue #26

internal/runtimeEnv/setup.go

@@ -65,7 +65,7 @@ func LoadEnv(file string) error {
 					case '"':
 						sb.WriteRune('"')
 					default:
-						return fmt.Errorf("RUNTIME/SETUP > unsupprorted escape sequence in quoted string: backslash %#v", runes[i])
+						return fmt.Errorf("RUNTIME/SETUP > unsupported escape sequence in quoted string: backslash %#v", runes[i])
 					}
 					continue
 				}