Update graph baselines to have a title passed as part of the url argument

When multiple baseline are present, they are hard to distinguish from each other.  This change allows the caller to give each baseline a title, which is displayed in the legend.

git-svn-id: https://llvm.org/svn/llvm-project/lnt/trunk@208133 91177308-0d34-0410-b5e6-96231b3b80d8
Update baseline's color selection

When there are many baselines on a LNT graph, they become hard to distinguish. This changes baselines to have a spread of colors, so they can be easily visually separated.

git-svn-id: https://llvm.org/svn/llvm-project/lnt/trunk@208134 91177308-0d34-0410-b5e6-96231b3b80d8