#165 EGifSpew leaks GifFileOut->SColorMap

[Ono-Sendai]

EGifSpew calls EGifPutScreenDesc, passing in GifFileOut->SColorMap as the GifColorMap parameter.

In EGifPutScreenDesc, a colour map object is created with GifMakeMapObject, and assigned to SColorMap. The old data pointed to by SColorMap previously is not freed.

(The whole copying of the colour map data is also redundant, copying from itself to itself)

[Eric S. Raymond]

Fix applied, thanks.

[Eric S. Raymond]

The fix I aspplied for this turns out to be incorrect, revealing a deeper issue about the design of the library that will take some further work.

[Eric S. Raymond]

Improved fix pushed.