Group links & permalinks cleanup

[johnjamesjacoby]

Improvements are necessary to bp-group-template.php:

• Output functions need to use esc_url()
• Should use trailingslashit() and usertrailingslashit()
• Logic should be broken out of apply_filters() calls
• Some functions missing filters
• Some functions have differing return/output parameters
• Missing PHPDoc blocks
• Using out-of-date functions & API's
• Code formatting improvements

[johnjamesjacoby]

​6451.01.patch is a first pass at addressing all of these concerns for URL related groups template functions.

Worth noting that:
*Most of these functions have not been modified since 1.0

• A few of these are no longer used
• There are gaps where new functions could be introduced, specifically the URLs generated inside of bp_get_group_join_button()

[boonebgorges]

Individual changes look fine to me. It would be great to see the broad categories of changes (esc_url() vs codestyling vs moving user_id fallback into the get_ variant etc) separated into different changesets. Also I see at least one usc_url().

[johnjamesjacoby]

usc_url() is my nemesis.

Will refresh the patch and/or split this apart.