Fix scripts/version: use git describe --tags ...

After tagging as 1.4 scripts/version was still producing jq-1.3-....
Also fix configure.ac to use git describe --tags
Update site news
Building docs fails on powerpc (#349)

Thanks @shym!!
Add note about cmd.exe quoting
Make the note about shell quoting appear on site
Add lib.h to dist file list
Detect endianness at configuration with Autoconf AC_C_BIGENDIAN feature
Merge pull request #400 from kdeme/master

Heuristic IEEE754 endianness autoconf detection

Use AC_C_BIGENDIAN, though it's not really the correct approach.  Autoconf ought to have provided a test specifically for IEEE754 endianness, since it can differ from integer/pointer endianness!
Make a better jq.1 when Ruby deps missing
Include links to 1.3 executables in gh-pages
Add links to Solaris 11+ executables
jqplay has a domain now
Add jqplay link to the site
Automatically update jq.1.prebuilt
Document the lambda nature of function args #391
Add `env` builtin
Fix typo; rename jq.1-prebuit to jq.1.prebuilt
Allow multiple functions with different arities
Fix Win64 jq.exe link on main page