Issue2

1. Simplified internal PICA format.

   No backwards compatibility.

2. PICA::Writer::Plus: 
    
    Set END_OF_RECORD to \N{LINE FEED}, because I would prefer a line separated file format. In other formats  \N{INFORMATION SEPARATOR THREE} is used as record separator. Schould we use it in addition?

3. PICA::Parser::Plus

    Record leader will be dropped while importing because usage is unclear.