cidian 0.1.0

• read_cidian() 现在可以将 SCEL、QCEL、QPYD、BDICT 和 BCD 文件读入统一的 cidian_dictionary 对象（初始实现）。
• 新增 cidian_formats()、cidian_entries()、cidian_metadata()， 以及用于打印、摘要和转换词典的 S3 方法（初始实现）。
• 新增 write_words()，把词典中的词语每行一个导出到文本文件， 可用作 jiebaRS 等工具的自定义词典。

• read_cidian() now reads SCEL, QCEL, QPYD, BDICT, and BCD files into a common cidian_dictionary object (initial implementation).
• Added cidian_formats(), cidian_entries(), cidian_metadata(), and S3 methods for printing, summarizing, and converting dictionaries (initial implementation).
• Added write_words() to export dictionary words to a text file, one per line, for use as a custom dictionary by jiebaRS and similar tools.