Avoid using deprecated vibe.d symbols.
add colNames and colNameIndicies to ResultSequence

- same as in ResultSet
detect nullable types and call nullify in toStruct
Merge pull request #36 from MartinNowak/columnNames

add colNames and colNameIndicies to ResultSequence
Merge pull request #37 from MartinNowak/nullify

detect nullable types and call nullify in toStruct
Make it depends on vibe.d's ~BoapNet branch