DynRPG: DynText - Implementation issues

[Mimigris]

More info about DirectMenuPatch at #2369.

Currently EasyRPG has some issues with the implementation:

• Using @write_text with a text ID that already exists should not allow overwriting the text present in the text ID (should be ignored)
• Using @append_line on a text ID should not reprocess the existing text of the picture (the existing text should keep using the current font, and keep using the same System graphic). (@append_text reprocesses the text as expected both for DynRPG and EasyRPG, so no change to do there)
• DynRPG supports specifying a picture ID to use as the target for those text ID operations as part of the DynRPG.ini file, as part of [DynTextPlugin] and with the argument PictureID=X in it (where X is the picture ID aimed; no specification of the PictureID means the PictureID is 1). Currently EasyRPG always considers the picture ID in use to be the picture of ID 1 and ignores this parameter.
• EasyRPG requires to have the picture of the ID to be created once, then will allow text IDs to be displayed no matter the status of the picture of ID 1. DynRPG instead will be able to display text pictures if the PictureID they are set to is currently set to be visible, and will not display them if no picture currently exists on the ID.
• The text displayed should not be affected by shake, even if it set to be displayed on a specific point of the map.
• The argument to parse a status (\a[X], where X corresponding to the ID of the specified status) does not work. It should display the name of the specified status if it exists, and be seen as empty if it doesn't exist.
• The argument to parse the class of a hero (\N[X]) doesn't work either, and instead parses the name of a hero.

Attempting to use @change_text on a text ID that does not exist currently displays a warning while DynText just ignores it, may want to move it to be considered as a debug info.
Similarly, parsing an invalid Item name, Item description, Skill name or Skill description currently displays a warning while DynRPG will just not display any text for it.

DynText bugs/issues:

• Displaying a text ID, then changing the System graphic in use and then using @append_line, @append_text or @change_text on it will not make the colours of the System graphic be loaded properly.
• Jumping to an 8th line will lead RPG_RT to an error (EasyRPG doesn't report anything so far), and a 7th line can already not always work.
• Sometimes when using commands, garbage characters are added at the end.