add sample files for Excel and Word

adjust testdata subfolders
add new tests for ExcelParser

change interface for IParsers.Parse; add ToxyDocument to implement Word
parser
implement WordParser; add IToxyProperties interface
Create README.md
add new test case for Word2007Parser
Update README.md
implement EMLParser
implement ToxyDom and ToxyEmail
rename varialb in ParserFactory
add RTFParser.cs file
fix a stupid bug of creating parser instance
implement ToDataTable for ToxyTable

adjust ToxySpreadsheet interfaces