Add Install Mode

- Added $install_mode in Class App instead
- Extracted the install business logic to a new Class Install
- Replaced all $a->module == 'install' with $a->install_mode

include/text.php

@@ -637,7 +637,7 @@ function logger($msg, $level = 0) {
 
 	// turn off logger in install mode
 	if (
-		$a->module == 'install'
+		$a->install_mode
 		|| !dba::$connected
 	) {
 		return;
@@ -709,7 +709,7 @@ function dlogger($msg, $level = 0) {
 
 	// turn off logger in install mode
 	if (
-		$a->module == 'install'
+		$a->install_mode
 		|| !dba::$connected
 	) {
 		return;