docs: update the tutorial to use GitHub's API
work with newer versions of automake

when using a newer automake, the autoreconf step fails with warnings:
"linking libtool libraries using a non-POSIX archiver requires 'AM_PROG_AR' in 'configure.ac' "

This happens for instance on ubuntu 13.10. 
Doing just that, adding 'AM_PROG_AR' to configure.ac fixes the problem.
Merge pull request #300 from lcd047/master

Fix building of the manual
Add `?`, `.[]?`, and `..` operators

Make XPath-like `//a/b` recursive structure traversal easier in jq,
which then becomes:

    ..|.a?.b?

The `?` operator suppresses errors about . not being an array or object.
The `..` operator is equivalent to calling the new `recurse_down`
built-in, which in turn is equivalent to

    recurse(.[]?)

Note that `..a` is not supported; neither is `...a`.  That could be add
added, but it doesn't seem worth the trouble of saving the need to type
a '|'.
Initial add of math functions.
Remove non-standard exp10()
Add missing trig functions and barebones test
Add cbrt (cube root)
Make jq --raw-output --unbuffered work

--unbuffered was only affecting the normal output case, not the --raw-output case. Make the two of them play together.

This also makes sure that the output is flushed *after* printing the newline, so a consumer doesn't lag a line behind.
Repair jv_show
Merge pull request #310 from arodland/master

Make jq --raw-output --unbuffered work
Make libm tests more portable
Add a recursive object merge strategy and bind it to *

This commit adds a jv_object_merge_recursive function, that performs
recursive object merging, and binds it to multiply when applied to
two objects.

Added docs and tests.

Closes #320
One more recursive merge test
Added `arrays` and other filters

Arrays, objects, numbers, strings, booleans, nulls, values (non-nulls)
-- these builtins filter out those inputs that don't match the name of
the builtin.

This fixes #322 and #324.
Document `arrays`, `objects`, ...
Also add `scalars`
Document `scalars`
Test `arrays` and friend filters
Merge pull request #278 from polyester/master

work with newer versions of automake