add "@" into first page of the keyboard and adjust some keys postion.
Merge branch 'master' of github.com:onyx-intl/booxsdk
add environment variable to set always update screen.
Merge pull request #24 from weihua/master

add environment variable to set always update screen.
add option of custom text size.
Merge pull request #27 from weihua/master

add option of custom text size.