Rename CharGroup to PtNode.

...id/inputmethod/latin/makedict/BinaryDictDecoderUtils.java

...id/inputmethod/latin/makedict/BinaryDictEncoderUtils.java

...android/inputmethod/latin/makedict/BinaryDictIOUtils.java

...c/com/android/inputmethod/latin/makedict/DictDecoder.java

.../inputmethod/latin/makedict/DynamicBinaryDictIOUtils.java

...rc/com/android/inputmethod/latin/makedict/FormatSpec.java

.../android/inputmethod/latin/makedict/FusionDictionary.java

...rc/com/android/inputmethod/latin/makedict/PtNodeInfo.java

...m/android/inputmethod/latin/makedict/Ver3DictDecoder.java

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

...id/inputmethod/latin/makedict/BinaryDictIOUtilsTests.java

.../inputmethod/latin/utils/UserHistoryDictIOUtilsTests.java

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

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

...roid/inputmethod/latin/makedict/FusionDictionaryTest.java