ca-shell.c: Store readline history to ~/.ca-shell_history

This is accomplished by calling read_history() and write_history().

Signed-off-by: Morten Hustveit <morten.hustveit@gmail.com>
During SELECT, reference fields by index rather than pointers

Using indexes makes it more convenient to pass data and metadata in arrays.

Signed-off-by: Morten Hustveit <morten.hustveit@gmail.com>
Merge branch 'master' of github.com:mortehu/cantera-table