Add description of using source_flattener to README
updated README to note the need for autoconf and libtool
.gitignore updates for intermediate build products
add README comment about how to run the tests
updated source coda to include macro prefixes from liberfa/erfa-fetch#7

closes #12
Updated README.rst and RELEASE.rst
Preparing release v1.0.0
Updated libtool version-info to get correct SONAME versions
try expr instead of bc
Merge pull request #15 from eteq/libtool-version-derive

Updated libtool version-info to get correct SONAME versions
added erfa taballs to gitignore