spearmint: Add specific message for no light grid

"light grid mismatch: 27054 points found, expected 0" is overly complicated
for saying map was compiled without light grid.
spearmint: Increase SHADER_MAX_VERTEXES to 1201 for EF2 maps

Some EF2 maps have triangle mesh surfaces with more than 1100 vertexes.
Increased from 1024 to an even 1200 (+ 1 for error checking).

Maps: dm_firstcontact, ent-deck16_engineering, ent-deck7c, m12-end, m3l1b-forever,
m4l1a-attrexian_station, m4l1b-attrexian_station, m4l2b-attrexian_station, m6l0-attack
spearmint: Allow loading Dark Salvation maps