Redoing code-highlighter.js and dxr.css for better file display 

## Fixes bugs: 1006108 and 1055142
- Here is how things used to work:
The file would be displayed as a table with two overlaying columns. Clicking the line number would change that line numbers background color, making it seem as if the user highlighted the code.
- That lead following problems:
  - long lines would be only partially highlighted
  - line numbers with more than 3 digits aren't displayed properly
- I fixed the above problems by standardisning the columns in a similar fashion like search results and tweaking the js to highlight both line number and code.
- The auto scrolling didn't work properly because of bad handling of strings and integers. I cleared that up and changed the way the url's are changed and processed.
 
 
## Changes to code-highlighter.js
- Added function sortRangeAsc which sorts selection ranges both as strings or arrays.
- In function generateSelectedArrays:
  - Changed the way multiSelected and singleSelected get their value (employed jQuery).
  - Made the function return sortedsingleLinesArray and  rangesArray.
- In function setWindowHash:
  - Removed variables singles and ranges, which are no longer used for the display of the hash.
  - Added a loop that eliminates singleLines which are already a part of a range.
  - Added a loop that adds lines and ranges to the hash in order:
    - example now:    #12-15,17,20-25,30-33,42
    - example before: #17,42,12-15,20-25,30-33
- In function getSortedHashLines:
  - Seperated reCleanup. Added cleaning of whitespace upfront.
  - Changed the way ranges are sorted form string sorting to newly added function sortRangeAsc.
  - Changed the way a range is added to rangesArray in order to account for backward ranges (150-120 and such).
  - Made firstRange take an array as value instead of a string so that it's value can be compared and scrolling made possible.
  - Modified the way highlights is cleaned form trash.
  - If something slips through the process above added testing for NaN in highlights.
  - Repaired the if block that determines the position to be scrolled to.
  - Made the function return singleLinesArray and rangesArray for later convenience.
- Big changes to the .line-number onClick events:
  - Moved the value assignment for variables to take place before the if block to avoid repetition.
  - lastSelected is now lastSelectedLine and includes both a .line-number and code element.
  - selected is replaced by selectedLineNums and selectedLineCode.
Let's make the formatting conform to the style guide: https://mozweb.readthedocs.org/en/latest/js-style.html#conditionals-and-loops.