Add convert command

[nwagner84]

Examples

PICA+ to Plain

$ pica convert --from plus --to plain tests/snapshot/data/algebra.dat
001A $01250:01-07-88                                                                                                                                     
001B $01250:24-04-19$t15:55:35.000                                                                                                                       
001D $09999:17-01-09                                                                                                                                     
001U $0utf8                                                                                                                                              
001X $00                                                                                                                                                 
002@ $0Ts1                                                                                                                                               
003@ $0040011569
...

PICA+ to PICA XML

$ pica  convert --from plus --to xml tests/snapshot/data/algebra.dat
<?xml version="1.0" encoding="UTF-8"?>                                                                                                                   
<collection targetNamespace="info:srw/schema/5/picaXML-v1.0" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="info:srw/schema/5/picaXML-v1.0">         
    <record>                                                                                                                                             
        <datafield tag="001A">                                                                                                                           
            <subfield code="0">1250:01-07-88</subfield>                                                                                                  
        </datafield>                                                                                                                                     
        <datafield tag="001B">                                                                                                                           
            <subfield code="0">1250:24-04-19</subfield>                                                                                                  
            <subfield code="t">15:55:35.000</subfield>                                                                                                   
        </datafield>                                                                                                                                     
        <datafield tag="001D">                                                                                                                           
            <subfield code="0">9999:17-01-09</subfield>                                                                                                  
        </datafield>
        ...
    </record>
</collection>

PICA+ to PICA JSON

pica convert --from plus --to json tests/snapshot/data/algebra.dat`
[[["001A",null,"0","1250:01-07-88"],[...],["070A","02","S","MACS","0","0000478"]]]

PICA+ to Binary PICA

echo -e "003@ \x1f0123456789\x1fab\x1e" | pica convert --from plus --to binary | hexdump -C
00000000  30 30 33 40 20 1f 30 31  32 33 34 35 36 37 38 39  |003@ .0123456789|
00000010  1f 61 62 1e 1d                                    |.ab..|
00000015

PICA+ to Import

$ echo -e "003@ \x1f0123456789\x1fab\x1e012A \x1fa123\x1e" | pica convert --from plus --to import | hexdump -C
00000000  1d 0a 1e 30 30 33 40 20  1f 30 31 32 33 34 35 36  |...003@ .0123456|
00000010  37 38 39 1f 61 62 0a 1e  30 31 32 41 20 1f 61 31  |789.ab..012A .a1|
00000020  32 33 0a                                          |23.|
00000023