templater: fix pad() to evaluate int argument and handle error

templater: drop redundant type conversion when evaluating integer argument A function argument may be an integer. In this case, it isn't necessary to convert a value to string and back to integer. Because an argument may be an arbitrary object (e.g. date tuple), TypeError should be caught as well.

templater: factor out function that evaluates argument as integer We have more bare int()s that may raise ValueError or TypeError. This function will be used to fix them.

chgserver: use basename for socket symlink Previously we use full path and the symlink may point to outside (unsafe) world if the directory is moved. This patch fixes it by only linking to basename of the target. Therefore the symbolic link and socket files will always stay in the same directory.