2015-03-29 ~ 2015-09-22  Wush Wu <wush978@gmail.com>
- Version 0.9.1
- Include two vignettes.
- Change the default behavior of `hashed.model.matrix`:
    - The `signed.hash` is disabled.
    - The output of `split` with type `\"existence\"` will filter the collision.
- Add a helper function to calculate the index of interaction.
- Add progress bar to `hashed.model.matrix`.
- Add the type `tf-idf` to split.

2015-01-01 ~ 2015-03-28  Wush Wu <wush978@gmail.com>

- Version 0.9
- Enhance the documentations.
- Rename the original API:
    - tag ==> split
    - hash_size ==> hash.size
    - is.create_mapping ==> create.mapping
- Change the default argument:
    - transpose ==> FALSE
    - is.dgCMatrix ==> TRUE
- The empty string after `split` is skipped.
- The attribute `mapping` returned by `hashed.model.matrix` is the indices in the matrix now.
- Add two API and add Michael Benesty to the Author list:
    - hash.mapping : extract the `mapping` table from the returned matrix by `hashed.model.matrix`.
    - hash.size : suggest a hash size.
- Add an API for documentation intToRaw and remove the package pack from Suggests .

2015-01-01  Wush Wu <wush978@gmail.com>

- Version 0.8.1
- Change the API
    - Default `transpose` to `FALSE`
    - Add the argument `is.dgCMatrix` and the default value is `TRUE`

- Version 0.8
- Use the implementation of murmurhash3 from the package digest
    - Update the author list
- Fix the following bugs
    - Undefined behavior due to big endian system
    - Inconsistent interaction result due to big endian system
    - Incorrect indices when expanding tag feature. See #27
- Correct some document errors in DESCRIPTION and Manual
