Add pinyin representations with and without tones to Entry

Herman,

I added some functionality to your CEDICT parser to add pinyin representations that include and exclude tone marks.  The new fields in the Entry struct are: 
```
Entry.PinyinWithTones
Entry.PinyinNoTones
```
The functions give you output like:
 ```
Entry.Pinyin = yi1 tuan2 huo3
Entry.PinyinWithTones = yītuánhuǒ
Entry.PinyinNoTones = yituanhuo
```
Commit 4e88c17 also converts the pinyin representation to lower case.  CEDICT has some entries with upper case initial letters for proper names such as places and this was causing some issues with a search interface I was writing.

Comments and feedback are welcome.  Thanks for doing all the hard work.  This has been very useful for me.

Bryan

I think this should probably be done by the user outside of the library, since otherwise it's not an accurate representation of what CEDict gives you (I imagine some people might like to show the upper-case version in their apps)