Track remaining changes in 0030919 that were not implemented in 2.26.0.

4. cleanup the blockHeader part

The Tests testHashLetters, testHashNumberAny and testHashLettersAny failing.

• invert the logic, do not search for a valid markdown heading, search for a valid "buglink" instead.
• Change regex to be more generous with the use of colons.
• Add test for the regular expression.

The Tests testHashLetters, testHashNumberAny and testHashLettersAny are successfully again afterward.

todo: Clarify what a valid issue mention is.

| input            | is issue mention     |
|------------------|----------------------|
| `#1`          | true                 |
| `#123 `          | true                 |
| ` #123 `         | true                 |
| `#123 `          | true                 |
| `#123 summary`   | true                 |
| `#123: summary`  | true                 |
| `#123:summary`   | true                 |
| `#123:: summary` | true but should not? |
| `#123summary`    | false                |
| `# 123:summary`  | false                |
| `# summary `     | false                |
| `# 123`          | false                |

Modify the regex to meet the mantis requirements.

see https://github.com/mantisbt/mantisbt/pull/1929

5. cleanup formatting process

• Rearrange the processing. Moving the Markdown part before ON == $s_text, return the result and do not doing further processing.
• Make MantisMarkdown know about the plugin config and process the links and mentions within the parser context
• mark all the methods that make use of $this->processAmpersand() as deprecated, because the output is no loger messed up.
• remove all methods which marked as "deprecated"

Parsedown provides a usefull method called unmarkedText, which make all "unmarked" strings accessible. Seems the right place to process the links.

see https://github.com/mantisbt/mantisbt/compare/master...grummbeer:mantisbt:markdown-cleanup-05-formatting

After that and merging all parts together the whole part looks very nice and its a huge impact for user experience.

The branches are all independent but could make it a cascading series. What do you think about? I am not experienced in contributing, so this may look strange to you, but I have no idea what the right approach is.

todo

• the tests are now failing because MantisMarkdown.php is getting the plugin config using plugin_config_get, which is not available inside the unit tests. Make it possible to pass a configuration to the MantisMarkdown?
• emails still not proceed with markdown. hidden deep inside string_insert_hrefs make a new api function to catch them?
• add prism to raise up the user experience.

Fixing this todos would be a really nice finishing point.