Fixed clang++ compilation warnings and single header version

• Fixed clang++ compilation warnings and UTF-8 BOM detection (with the help of @tamaskenez)
• Fixed compilation errors that occurred when including single header csv.hpp in multiple files

Added JSON serialization

CSVRow objects now have to_json() and to_json_array() methods with proper string escaping and column slicing/rearranging. The CSVFormat interface is now also more robust.

Fixed bug where user provided column names are overwritten

Fixed bug #44 where user provided column names are overwritten if delimiter guessing is used.

Added whitespace trimming

Added efficient whitespace trimming which can be enabled by calling trim({ … }) on CSVFormat.

CSVWriter and CSVField::get<>() Improvements

• Integrated Hedley library
  • Possible performance increase on older compilers due to use of restrict, pure, etc.
• Better handling of integer types with get()
  • get<>() is now supported for all signed integer types
  • Removed complications regarding the (mostly) useless long int type
• CSVWriter now accepts deque<string> and list<string> as inputs
• Updated Catch to latest version
  • Refactored unit tests

Performance + API Improvements

Found a bug in the previous release

Performance + API Enhancements

• Improved performance by storing all CSVRow data in contiguous memory regions
  • Numbers based on my computer
    • Disk parsing speed: 220 MB/s
    • In-memory parsing speed: 380 MB/s
• Improved CSVFormat interface

Memory Fix

• Fixed memory issues reported by Valgrind
• Fixed segfaults that occurred in Microsoft Visual Studio debug builds

C++11 Compatibility

CSV library should now be compatible with C++11 by using a third-party string_view implementation. If C++17 is detected, then std::string_view will be used.

Floating Point Parsing Fix

Merge pull request #16 from vincentlaucsb/double-parse-fix

Fixed floating point parsing bug #15