Compress the CSS in css2js.js, by removing comments & indentation

The file webodf.css is currently more or less directly converted into a string by css2js.js. Including the license header, all other comments and the indentation.

Based on heuristics and my little CSS syntax knowledge (so please better check) I propose to do some simple compression when creating the string. Spares some 5K bytes on webodf.js

Name | Size Before | Size After
--------|----------|-----
webodf/webodf.css.js| 16288 | 10929
webodf/webodf.js| 355267 | 349908
If you separate the (trim extra whitespace & blank-lines) from (remove comments), these 3 regexps can be simplified a bit as follows:
```
data = data.replace(/\/\*([\r\n]|.)*?\*\//g, ""); // remove comments
data = data.replace(/(^\s*)|(\s*$)/gm, ""); // remove leading & trailing whitespace
```