Data type: string with tags

--Syntax--
Strings in [[type:value|text values]] can contain markup tags.
These tags affect the presentation and sometimes the behaviour of the text.

A tag is something like @"<tag>some text</tag>"@, similair to HTML.
Tags are closed by the same tag with a @/@ before it.

To represent the character @"<"@ in a tagged string use @"\<"@ in script code.
This is written as the character with code 1 in files.

--Basic markup--
! Tag			Description
| @"<b>"@		The text inside the tag is bold.
| @"<i>"@		The text inside the tag is italic.
| @"<sym>"@		The text inside the tag is rendered as symbols, if a [[prop:style:symbol font]] is set for the text box.
| @"<line>"@		Line breaks inside this tag use the [[prop:style:line height line]], and they show a horizontal line.
| @"<soft-line>"@	Line breaks inside this tag use the [[prop:style:soft line height]].
| @"<atom>"@		An atomic piece of text. The cursor can never be inside it; it is selected as a whole.
			The program automatically inserts <atom-soft>
| @"<code>"@		The text inside the text is rendered in a monospace font. This is used for syntax highlighting script code.
| @"<code-kw>"@		The text inside the text is highlighted as a keyword in source code.
| @"<code-str>"@	The text inside the text is highlighted as a string in source code.


--Other tags--
! Tag			Description
| @"<kw-?>"@		Indicates that the text inside it is a keyword. This tag is automatically inserted by
			The [[fun:expand_keywords]] function.<br/>
			There are four versions, indicating whether or not reminder text is shown:
			* @"<kw-0>"@, Reminder text hidden, by default
			* @"<kw-1>"@, Reminder text shown, by default
			* @"<kw-a>"@, Reminder hidden manually
			* @"<kw-A>"@, Reminder shown manually
| @"<sep>"@		A separator between fields. This tag is automatically inserted by the [[fun:combined_editor]] function.<br/>
			Inserting this tag manually will confuse that function!<br/>
			This tag can never be selected, and its contents can not be edited.
| @"<sep-soft>"@	Like @"<sep>"@, only hidden. This is inserted by [[fun:combined_editor]]
| any other tag		Other tags are ignored.

--Related functions--
The following script functions deal with tags:
| [[fun:tag_contents|tag_contents / tag_contents_rule]]
				Change the contents of a specific tag.
| [[fun:remove_tag|remove_tag / tag_remove_rule]]
				Remove a tag, keep the contents.
