add with_escape for csv::ReaderBuilder

[kazuk]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

Allow read non-standard CSV.

background: I plan to read external CSV source, that have non-standard escape rule.

Describe the solution you'd like

• add escape: Option<u8> field to ReaderBuilder.
• add pub fn with_escape( mut self, escape: u8 ) -> Self method to ReaderBuilder.
• optional with_quote for quote setting
• add pub(crate) fn from_builder( builder: ReaderBuilder ) -> Self to Reader
  and handle builder options
• change pub fn build<R: Read + Seek>(self, mut reader: R) -> Result<Reader<R>> on ReaderBuilder
  call from_builder

Describe alternatives you've considered

add pub fn from_csv_reader( csv_reader: crate_csv::Reader ) ->Self to Reader
use custom builded csv_reader