Unify geocache log texts

[kojoty]

cache_log DB table contains currently:

• text_htmledit with values: 0|1
• text_html with values 0|1|2

I believe that with our new DB update mechanism it should be easy to cleanup it.
We should store in Db just safe log text with simple HTML tags in UTF, and be sure there is no need to do any "magic" to display it.

Columns text_htmledit and text_html shoudl be removed from Db then.

[kojoty]

@following5
I believe you're the most experienced person in this subject.
You wrote here: #1218 (comment)
that the problem is the old OCPL code.

I would like to fix it but I need to understand how to deal with current DB content.

Can you please explain here what should be done to clean up this in DB or if this is not possible why it can be done. What means values: 0-1-2 etc.

Thanks.

[following5]

text_htmledit is obsolete for OCPL, should no longer be evaluated in OCPL code.

text_html should have this content:

0 = old plain text log
1 = old log with double-encoded HTML, i.e. htmlentities(HTML log text)
2 = clean HTML

So to eliminate text_html, the 0-format logs should be htmlentities()-encoded once, and the 1-format logs should be html_entity_decode()ed once. Then all logs would be treated like text_html = 2, i.e. text_html would become obsolete.

BUT: There may be logs with text_html 0 or 1 which actually do not have this format, and which would be garbled by this processing (see e.g. #1218 (comment)). So it should be checked first if the existing format-0 and -1 logs in the database are really all encoded in this way. E.g. there should be no < or > characters in text_html=1 logs, and not HTML tags in text_html=0 logs.

Note that OKAPI implemented an ugly hack to emulate the double-encoding, see opencaching/okapi#413. But I think this does not need special treatment: The one-time decoding of html_text=1 logs should resolve that OKAPI encoding.

(The only OKAPI related change here would be to no longer initialize / update the text_htmledit and text_html fields.)

[following5]

1 = old log with double-encoded HTML, i.e. htmlentities(HTML log text)

Or maybe some combination of htmlentities() and nl2br() encoding. Suggest to review the old log.php code.