dispatch: don't stack trace on commands like `hg .log` This used to stack trace because it raised a util.Abort which wasn't handled in this block. We now handle it. Additionally, we error out earlier instead of plodding on and showing the "log" entry of the plain `hg help` output.

gitweb, monoblue: port highlighting linked lines from paper This is adapted from 41c4bdd1d585, fbfe5748ef3e and f3393d458bf5.

gitweb, monoblue: fix vertical align of spans in .sourcelines Empty lines in file view could produce an inexplicable margin before the next line (most noticeable in browsers on webkit/blink engine). That was making empty lines seem taller than the rest. Instead of using default vertical align, let's set it to 'top'. This issue is actually present in paper, and only recently got into gitweb (2239626369f5) and monoblue (119202d4d7a4). There's a bit more to it in paper, so that will be dealt with in a future patch. Recipe to see live: preferably using a webkit/blink browser, such as chromium, browse a file with empty lines, e.g. https://selenic.com/hg/file/3.5/README#l8 Selecting a block of text that includes empty lines will reveal white "breaks" in the selection. Highlighted line (#l8) also shows such a break below itself.