now we not only display the longest matching words
but also the shorter ones, in case the user wants to type a word that
is not yet in the database
added C header file in include directory
change named of c binding functions for  vector of string to be named vec_string_* instead
of suggestion_ so that it's more generic
added a function in C binding and rust binding to transform a string into a vector of string of pinyin
token
Merge branch 'master' of github.com:pinyin-tools/librustpinyin