Normalization of template tag filters

[Funkatronic]

The filters for the template tags, specifically, title, content and excerpt, are not very uniform. Some of them have a filter for their get_the variant, but not others. Only the_title sends the post id through the filter while the others do not.

The included patch does the following:

• Add get_the filters to the proper functions for get_the_title, get_the_content, get_the_excerpt
• Added post_type specific variants of the filters ( ex. the_title_{$post->post_type}
• All filters now pass the post id as a second argument

[Caspie]

A very good idea for example for a cases when you want to hook the_content but also want to add some conditional logic based on the post type.