Needs better message for "Invalid spellcheck line"

[naoliv]

While using this as a custom tagchecker:

way  : W : highway == * && surface != * # highway without surface type
way  : I : highway == * && maxspeed != * # highway without max speed

I saw that nothing was happening.
Then after a lot of investigation I saw this (after running josm from a shell):

Invalid spellcheck line: way  : W : highway == * && surface != * # highway without surface type
Invalid spellcheck line: way  : I : highway == * && maxspeed != * # highway without max speed

So first problem: it should display inside josm a graphical message that something is wrong with the config file.

Then tried to understand why it was telling me that these lines were wrong. After a long time I saw that it was missing this as the first line of my config file:

# JOSM TagChecker validator file

Second problem: it should just read and interpret the config file, ignoring this header or, at least, give the user a better message on why the config file was invalid (in fact it was valid, but missing just a line)

[simon04]

Second problem is addressed in patch (for discussion). Concerning first problem, I'm not sure whether that is intended, i.e., to not interrupt start in case of a erroneous tagchecker file.

[stoecker]

This patch is wrong. We have 3 types of files. Simple words file, the tagchecker file and the ignore file. The words file is very simple and has no header.

[Don-vip]

TagChecker is being replaced by new MapCSS-based TagChecker, see #9414.