Document `error/1`
Add `try EXP catch EXP`
Add general `?` operator
Add support for negative indices for .[]; fix #462

Signed-off-by: Nicolas Williams <nico@cryptonector.com>
Add `foreach` and `limit`
Add `any/N` and `all/N` x N in (1, 2) (fix #455)

    Contributed by @pkoppstein.
Better check for lib has only functions (fix #138)
$var["foo"]=1 can't work as expected; doc fix #236
Add missing backtick in manual
Document `path(path_expression)` builtin
Explain `foreach`'s powers a bit more
Add `break` builtin for `foreach`
jv_show() should be able to display invalid values
jv_invalid() shouldn't allocate

jv_invalid() should behave like jv_invalid_with_msg(jv_null()), and
neither should allocate memory, because neither ought to need to.
exec_stack.h was not using jv_mem_realloc()
Make `any/2` and `all/2` efficient using `foreach`
`limit` should use `break`
`error(x)` should not `tostring` its arg; fix #466
Make C-coded built-ins take `jq_state *` argument