Cleanups: isResult() more used, readability improved (#5608)

Cleanups: isResult() more used, readability improved (#5608)

* [diaspora]: Maybe SimpleXMLElement is the right type-hint?

* Changes proposed + pre-renaming:
- pre-renamed $db -> $connection
- added TODOs for not allowing bad method invocations (there is a
  BadMethodCallException in SPL)

* If no record is found, below $r[0] will fail with a E_NOTICE and the code
doesn't behave as expected.

* Ops, one more left ...

* Continued:
- added documentation for Contact::updateSslPolicy() method
- added type-hint for $contact of same method
- empty lines added + TODO where the bug origins that $item has no element 'body'

* Added empty lines for better readability

* Cleaned up:
- no more x() (deprecated) usage but empty() instead
- fixed mixing of space/tab indending
- merged else/if block goether in elseif() (lesser nested code blocks)

* Re-fixed DBM -> DBA switch

* Fixes/rewrites:
- use empty()/isset() instead of deprecated x()
- merged 2 nested if() blocks into one
- avoided nested if() block inside else block by rewriting it to elseif()
- $contact_id is an integer, let's test on > 0 here
- added a lot spaces and some empty lines for better readability

* Rewrite:
- moved all CONTACT_* constants from boot.php to Contact class

* CR request:
- renamed Contact::CONTACT_IS_* -> Contact::* ;-)

* Rewrites:
- moved PAGE_* to Friendica\Model\Profile class
- fixed mixure with "Contact::* rewrite"

* Ops, one still there (return is no function)

* Rewrite to Proxy class:
- introduced new Friendica\Network\Proxy class for in exchange of proxy_*()
  functions
- moved also all PROXY_* constants there as Proxy::*
- removed now no longer needed mod/proxy.php loading as composer's auto-load
  will do this for us
- renamed those proxy_*() functions to better names:
  + proxy_init()           -> Proxy::init()         (public)
  + proxy_url()            -> Proxy::proxifyUrl()   (public)
  + proxy_parse_html()     -> Proxy::proxifyHtml()  (public)
  + proxy_is_local_image() -> Proxy::isLocalImage() (private)
  + proxy_parse_query()    -> Proxy::parseQuery()   (private)
  + proxy_img_cb()         -> Proxy::replaceUrl()   (private)

* CR request:
- moved all PAGE_* constants to Friendica\Model\Contact class
- fixed all references of both classes

* Ops, need to set $a here ...

* CR request:
- moved Proxy class to Friendica\Module
- extended BaseModule

* Ops, no need for own instance of $a when self::getApp() is around.

* Proxy-rewrite:
- proxy_url() and proxy_parse_html() are both non-module functions (now
  methods)
- so they must be splitted into a seperate class
- also the SIZE_* and DEFAULT_TIME constants are both not relevant to module

* No instances from utility classes

* Fixed error:
- proxify*() is now located in `Friendica\Util\ProxyUtils`

* Moved back to original place, ops? How did they move here? Well, it was not
intended by me.

* Removed duplicate (left-over from split) constants and static array. Thank to
MrPetovan finding it.

* Renamed ProxyUtils -> Proxy and aliased it back to ProxyUtils.

* Rewrite:
- stopped using deprecated NETWORK_* constants, now Protocol::* should be used
- still left them intact for slow/lazy developers ...

* Ops, was added accidentally ...

* Ops, why these wrong moves?

* Ops, one to much (thanks to MrPetovan)

* Ops, wrong moving ...

* moved back to original place ...

* spaces added

* empty lines add for better readability.

* convertered spaces -> tab for code indenting.

* CR request: Add space between if and brace.

* CR requests fixed + move reverted
- ops, src/Module/*.php has been moved to src/Network/ accidentally
- reverted some parts in src/Database/DBA.php as pointed out by Annando
- removed internal TODO items
- added some spaces for better readability