On NMRiH and possibly other games that use the Maphacks system,
entries that are modified using that system are rendered with tab
characters stripped out - see CNMRiHMapHackManager::GetEntDataString.
That results in there being no separators at all between keys and
values, as Maphacks receives the serialized string from Entity Lump
Manager.
This commit changes the key / value separator character to use
spaces instead.
This discovery upsets me greatly.
Fixes#1833.
This change ensures that the iterator values used by `std::distance`
is correct. Having the emplace within leads to the possibility of
`m_Entities.begin()` being invalidated due to reallocations.
