smart conversion of compiling time

[mmarras]

Hi,
I am usually compiling bigger projects. But even if it is just one page with a lot of images, compilation time can get large. So I get info bubbles like Successfully build LaTeX in 29599 ms. How about making this output human readable. Do we need ms precision when compilation takes minutes?

[ashthespy]

IMO this is a leftover when I was trying to speed up build times, and was interested in having some metrics. I will refactor this out to be human readable when I work on the next update..
If someone is willing to make a PR, please also feel free!