comments-nav: add dividers according to the UI specs.

comments: make add arrow slightly smaller, and not hide the line numbers when hover.

diffs: add new diffs to pull request page

diffs: fix bug where relevant pull request comments were not being shown on single changeset page, fixes #4311

ux: add hidden comments indicators plus style tweaks * add hidden comments indicator in diff lines * make no new line at end of file marker red * fixes bug where show/hide comments was not changing message refs #4311

api: add backward compatible info required for rhodecode-index.

system-info: fix display of text in system inodes.

repo-group-schemas: refactor repository group schemas. - fixes #4133 - refactor to make it behave like repo schemas - chain validation fixes - nicer error messages - consistent permission checks

repo-schemas: refactor repository schemas and use it in API update/create functions. - now it uses consistent way of serializing/validating data - parent groups are consistenty handled by name parameter - fixes #4133 - fixes other problems with bad data - changes API slightly - validation chain ordering, first permissions, then uniqness. Helps prevent resource disvovery

repo-group: add path to exception when directory under which repo group should be created already exists.