Extend jv_number to use decNumber for storing number literals. Any math
operations on the numbers will truncate them to double precision.
Comparisons when both numbers are literal numbers will compare them
without truncation.
Delay conversion of numbers to doubles until a math operation is performed,
to preserve precision. A literal jv_number will only need conversion to
double once, and will reuse the resultant double on subsequent
conversions.
Outputting literal jv_numbers preserves the original precision.
Add strong pthread requirement to manage contexts/allocations for
converting numbers between their decNumber, string, and double formats.
JV_PRINT_COLOUR was part of the public libjq headers and was removed as
part of 2d05b54. While JV_PRINT_COLOR is definitely the preferred
spelling this side of the pond, we shouldn't just remove otherwise
exposed enum values.
Leonid S. Usov