hgk: simplify tags parser As when hg tags is being called without -v option, it returns lines with two elements in each, we can just interate them as if it were a usual Tcl list using foreach and two variables. Line endings and whitespace don't matter when doing so, so we may keep them as is. When we're processing the lines, tag variable is assigned a tag name, and rev is a string in form of revision:hash which we can split on colon. As Tcl8.4 lacks lassign command, and using lindex makes code a bit less readable, we use foreach to iterate over two-element list.