Introduce NgramProperty in Java side.

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

...com/android/inputmethod/latin/makedict/NgramProperty.java

.../com/android/inputmethod/latin/makedict/WordProperty.java

.../android/inputmethod/latin/utils/CombinedFormatUtils.java

.../com/android/inputmethod/latin/BinaryDictionaryTests.java

...tmethod/latin/makedict/BinaryDictDecoderEncoderTests.java

...m/android/inputmethod/latin/makedict/Ver2DictDecoder.java

...m/android/inputmethod/latin/makedict/Ver4DictDecoder.java

...m/android/inputmethod/latin/makedict/Ver4DictEncoder.java

...tool/src/com/android/inputmethod/latin/dicttool/Diff.java

...tool/src/com/android/inputmethod/latin/dicttool/Info.java

...ndroid/inputmethod/latin/dicttool/XmlDictInputOutput.java