[RFE] Option to not merge vertexes when opening map

[DaniJ]

RFE: An option under preferences which disables the merging of vertexes, unpacking of sidedefs, etc..., when opening a map.

Naturally, such options should be disabled by default but I would find it very useful to be able to use DB2 as development tool for this purpose. Currently I am resorting to an older, clunkier map editor.