sql.lang: Correct number matching, add new keywords; file.sql: Add new cases

Well, I took your suggestion and looked at c.lang number patterns. It turns out it needed some fiddling, but at least all cases I was able to come up with are displayed correctly. I also checked if all these cases (especially the corner ones) are handled by PostgreSQL and they are (like e.g. .4e which translates to 0.4 * 10^0). There are additionally some new cases in file.sql. There is also range operator (e.g. 3..8), where dots were mistakenly taken as part of fp number, but now they are not. You're welcome to merge these, if you find it useful. 8) Regards — TK