Add checkout.h to git2.h.

Also correcting some documentation strings.

include/git2.h

@@ -38,6 +38,7 @@
 #include "git2/config.h"
 #include "git2/remote.h"
 #include "git2/clone.h"
+#include "git2/checkout.h"
 
 #include "git2/attr.h"
 #include "git2/branch.h"

include/git2/checkout.h

@@ -40,7 +40,7 @@ typedef struct git_checkout_opts {
  * @param repo repository to check out (must be non-bare)
  * @param opts specifies checkout options (may be NULL)
  * @param stats structure through which progress information is reported
- * @return 0 on success, GIT_ERROR otherwise (use git_error_last for information about the error)
+ * @return 0 on success, GIT_ERROR otherwise (use giterr_last for information about the error)
  */
 GIT_EXTERN(int) git_checkout_head(git_repository *repo,
 											 git_checkout_opts *opts,
@@ -54,7 +54,7 @@ GIT_EXTERN(int) git_checkout_head(git_repository *repo,
  * @param ref reference to follow to a commit
  * @param opts specifies checkout options (may be NULL)
  * @param stats structure through which progress information is reported
- * @return 0 on success, GIT_ERROR otherwise (use git_error_last for information about the error)
+ * @return 0 on success, GIT_ERROR otherwise (use giterr_last for information about the error)
  */
 GIT_EXTERN(int) git_checkout_reference(git_reference *ref,
 													git_checkout_opts *opts,

include/git2/clone.h

@@ -30,7 +30,7 @@ GIT_BEGIN_DECL
  * @param workdir_path local directory to clone to
  * @param fetch_stats pointer to structure that receives fetch progress information (may be NULL)
  * @param checkout_opts options for the checkout step (may be NULL)
- * @return 0 on success, GIT_ERROR otherwise (use git_error_last for information about the error)
+ * @return 0 on success, GIT_ERROR otherwise (use giterr_last for information about the error)
  */
 GIT_EXTERN(int) git_clone(git_repository **out,
 								  const char *origin_url,
@@ -46,7 +46,7 @@ GIT_EXTERN(int) git_clone(git_repository **out,
  * @param origin_url repository to clone from
  * @param dest_path local directory to clone to
  * @param fetch_stats pointer to structure that receives fetch progress information (may be NULL)
- * @return 0 on success, GIT_ERROR otherwise (use git_error_last for information about the error)
+ * @return 0 on success, GIT_ERROR otherwise (use giterr_last for information about the error)
  */
 GIT_EXTERN(int) git_clone_bare(git_repository **out,
 										 const char *origin_url,