Add a functionality to boost scores of personalization dictionary

java/res/values/strings.xml

java/src/com/android/inputmethod/latin/LatinIME.java

...com/android/inputmethod/latin/settings/DebugSettings.java

.../src/com/android/inputmethod/latin/settings/Settings.java

...om/android/inputmethod/latin/settings/SettingsValues.java

...utmethod/latin/utils/UserHistoryForgettingCurveUtils.java