Add Conference (5th tier England) data

[jalapic]

5th tier has been a national league since 1979/80 season - add data.

Note: check maketable_eng function for different tie-breaking and points procedures up to 1981/82 season.

[jalapic]

Have added data from 1999/2000 - 2016/17. Can get results from prior to this (league came into existence in 1979/80) but cannot find a source that also has dates of matches. Will add when can find it - and also change table function then.

[jalapic]

@RobWHickman did this - needs updating but exists.

[RobWHickman]

I think the data is really interesting at this level but I would strongly caution about updating it- at this level so many teams change their names, or have ambiguous names, you really want to set aside a weekend just to update data

[jalapic]

[jalapic]

because I'm a York City fan - I have motivation to try and get the data all the way down to the 6th tier....... or further should we get relegated even more in the future.