Parses value with sig and dec detection.

- v
- v(unc)[;sig;dec]
Use different number format for value and uncertainty.
Adds value renderer

The renderer will use different decimal formats for small, normal and
big numbers.
Accelerator from string

finish #2827
Document ListenableFuture.Status
Add min/max search for arrays

finish #2842
Release parent version 2.1

finish #2870
Release core version 2.1

finish #2871
Release data version 2.1

finish #2873
Release fileresources version 2.1

finish #2876
Release initfileparser version 2.1

finish #2877
Release math version 2.1

finish #2878
Release reflection version 2.1

finish #2879
Release threads version 2.1

finish #2880
Release exec version 2.1

finish #2874