Fix typo
Add tag example
Move all variable declarations to the top of the block
git_checkout_opts -> git_checkout_options
git_revert_opts -> git_revert_options
Merge pull request #2153 from mekishizufu/tag_example

Add a tag example
Merge pull request #2028 from libgit2/options-names

Rename options structures
Update clar to e1990d6
Merge pull request #2170 from ethomson/clar

Update clar to e1990d6