Export hook arguments as an array and display them properly

Formerly: #51
Fixes #50
Remove debugging code
Fix hook importing
Add the hook type as metadata when importing a hook

Fixes #58
Don't attempt to save 'arguments' metadata for classes

See #41
Introduce import_method() to import method data

An attempt was being made to add some method metadata to the class,
which was causing undefined index notices. This moves that out into the
new `import_method()` method.

Fixes #41
Formerly: #62 (importing hooks within methods; may be closed)
Import more class data

We export ‘extends’, ‘implements’, and ‘properties’, but we weren’t
importing them.
Update README.md

Be specific about what it actually produces.
Merge pull request #71 from GaryJones/patch-1

Update README.md
Export the structural element a doc tag refers to

Fixes #35
Fix a fatal error when generating from a directory

Fixes #73
Merge pull request #74 from JDGrimes/issue-73

Fix a fatal error when generating from a directory
Export the ending line number for structural elements

Fixes #12
Merge pull request #75 from JDGrimes/issue-12

Export the ending line number for structural elements
Merge pull request #72 from JDGrimes/issue-35

Export the structural element a doc tag refers to
Merge pull request #64 from JDGrimes/issue-41

Don't attempt to save 'arguments' metadata for classes
Merge pull request #63 from JDGrimes/issue-58

Add the hook type as metadata when importing a hook
Merge pull request #60 from JDGrimes/fix-hook-importing

Fix hook importing
Merge pull request #59 from JDGrimes/issue-50-2

Export hook arguments as an array and display them properly
apply_filters_ref_array() is a hook function

Fixes #54