highlight multiple lines

We can now highlight multiple lines, adding #L1-L2 to the hash.
We can select the ending line with shift + click.

Closes travis-ci/travis-ci#1829
extract the log lines selector into a separate component
store the last selected line and use it as the other end for multiple selection
Merge pull request #240 from dmathieu/multiple_lines

Highlight multiple lines
Removed duplicate duration icon