[texdoc] Some small bugs and more

[朝倉卓人]

Hello Karl, Norbert, and everyone

I read a part of texdoc source code (for understanding the scoring scheme)
and found some small problems in it.

First, texdoc doesn't check if they actually have an argument (which should
be a path to the file) so if we execute a command `texdoc --just-view` and
that will result to rise an internal error like:

	[string "..."]:53: attempt to concatenate a nil value

I think it is better to print usage text instead of this.

Secondly, some comments in score.tlu are not telling truths. For example,
on line 155, it says that

> if basename is bad, score gets < 0

but actually, texdoc gives 0.1 (> 0) for that case.

Thirdly, this is very simillar problem to the second one, some debug messages
seem that they also not telling the truths.

I think I can fix these problems, so may I join the project on puszcza?

And I also read TODO of the project and be interested in the following part:

> Searching by macro name???
>     - http://tug.org/pipermail/tex-live/2010-May/025832.html
>     - other ideas?

I thought that if texdoc has a function like "fuzzy search", it will be also
useful especially for people who are looking for new packages.

Best regards,
Takuto

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Takuto Asakura
Dept. of Bioinformatics and Syetems Biology,
Faculty of Science, The Univ. of Tokyo.
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