refs: Add `git_referene_target_peel`
refs: Check alloc is cleaner
refs: Do not union the peel
Merge pull request #1475 from libgit2/vmg/refs-peel

Allow access to the cached peel data in packed-refs
repository: Doc fix
use a longer string for dummy data in test to avoid conflicting w/ index
Merge pull request #1478 from ethomson/win32_typechange_test

use a longer string for dummy data in test to avoid conflicting w/ index
Return error for empty name/email
treebuilder: don't overwrite the error message
Merge pull request #1482 from nviennot/error-name-email

Return error for empty name/email
Add filesystem iterator variant

This adds a new variant iterator that is a raw filesystem iterator
for scanning directories from a root.  There is still more work to
do to blend this with the working directory iterator.
Make workdir iterator use filesystem iterator

This adds some hooks into the filesystem iterator so that the
workdir iterator can just become a wrapper around it.  Then we
remove most of the workdir iterator code and just have it augment
the filesystem iterator with skipping .git entries, updating the
ignore stack, and checking for submodules.
More filesystem iterator cleanup

Renamed the callback functions and made some minor rearrangements
to clean up the flow of some code.
More filesystem iterator tests

Refactors the helper function that builds a directory hierarchy
and then made use of it to try more variations on filesystem
iterator tests.
Fix uninitialized var warnings
Fix fs iterator test on case sensitive fs
Fix win64 warnings
Fix workdir iterator leak

When attempting to create a workdir iterator for a bare repo,
don't leak the iterator structure.