1.7.4 release

add WP writeProtect support (#58)

- solve #57 add support for WriteProtectPin
- add writeProtectPin as optional parameter in **begin()**
- add **bool hasWriteProtectPin()**
- add **void allowWrite()**
- add **void preventWrite()**
- add **void setAutoWriteProtect(bool b)**
- add **bool getAutoWriteProtect()**
- optimized **waitEEReady()**
- update keywords.txt
- update readme.md