Finally, no more RC or beta

It's been years pushing forward beta releases and RC releases. I believe we can drop that and name this release version 6, properly.

• Fixes #287
• Fixes #275
• Fixes #276

breaking change

• Drops support for Postgres 8.x
• If running on a subfolder (as requested an implemented on #28 ) you must configure it explicitly on your config.inc.php or config.yml. See "Running Inside a Subfolder"

Enhancements, Bugfixes and cleanup

• Scripts required from CDN (jquery, jquery-ui, etc) are now loaded locally.
• Layout of static assets has been changed to differentiate own vs vendor scripts
• Repairs Codemirror highlighting #256
• Minimum required version is PHP 7.1
• Adds support for PG 12 (in the future, PG13, PG14 and onward will fallback to PG 12 if there isnt a class for them) #243
• Bugfixes when browsing and searching #245 #246 #251
• Repairs index display under PG12 #253
• Null fields are marked as such (in the checkbox) when editing or inserting a record #254
• Repairs composer script referencing bad path
• Removes usage and mentions of plugin manager
• Adds support for an optional config.yml that overrides matching keys on config.inc.php #195

Release Candidate 1

Mild refactor to remove unneded dependencies and encapsulate most boilerplate while preserving flexibility.

• Debug tools such as Kint and PHP Console are now dev-dependencies. If not found on the project they will be polyfilled with noops
• src/lib.inc.php had a lot boilerplate code that is now encapsulated (for example in src/classes/ContainerUtils.php)

Enhancements to materialized view operations and insert/edit rows

• When dealing with materialized views, pass an extra parameter to Database controllers to let them differentiate between regular views and materialized views
• When inserting or editing table rows, if a given field has the null checkbox checked, add an event listener to uncheck the checkbox if the content field has changed and is non empty
• The method that draws the row update/insert form is now separate from the one that actually performs the update/insert. Previously it was the same method receiving a boolean flag.
• TODO: row update and insert logic are pretty similar. Such code should be moved to a trait that DisplayController and TableController would use to avoid useless repetition.
• TODO: row update shouldn't be part of DisplayController. It is intrinsecally a table operation and should be dealt with in TableController.

Enhancements and bugfixes

• Fixes falsy values displayed as NULL (#196).
• Sets correct content type headers when exporting schema to screen output
• Simplifies roles and privileges methods
• When inserting a new row, check the null input for empty fields that allow null values
• Avoid passing SQL in the query string when inspecting a column distinct values
• Export form has been extracted to a trait to reduce repetition (most of it is common to tables, views and matviews)
• Ensure server, database and table request params gets defined on hidden inputs when browsing a table