fix /alias trying to add an already existing command again after having it modified, resulting in an unnecessary error while still changing the alias
let calc return the results with unicode operators rendered, and remove an redundant condition in if
make if, math, calc and random command output consistent in naming

* numbers and values become numbers to supply actual type information
* operators and functions become operators
* operators that compare are now relation operators or just relations to comply with computer science and mathematics definition
document some variables time units
report gametime and optional time till suddendeath or timelimit additional to servertim in /time command
name variables for maintainability
Merge branch 'refactor/cleanup' into coins
fixing s_mute cvars not muting environment sounds (via loops) with the dma backend in effect
add s_mute support for background tracks like they get used for the start menu/intro
Merge pull request #169 from t4im/coins