Inline symbols are lost when saving a mapfile

[dmorissette]

If we load a mapfile and then save it back using MapServer's msSaveMap() then 
inline symbol definitions are lost.

I think the solution is to add an 'inline' flag in the symbolObj to mark inline 
symbols as we parse them from the mapfile, and then implement a writeSymbol() in 
mapfile.c to write back all the inline symbols in msSaveMap().

Do you agree with that change, Steve?

If we do it then we should apply that change to both 3.6.1 and 3.7 since it is 
required by our MapLab suite.

[dmorissette]

Steve confirmed that this change is OK with him, but only once he's done his 
current work in mapfile.c to add styleObj and remove paletteObj

[jlacroix]

A inline flag is added in mapserver 3.6 and 3.7. msSaveMap() now call
writeSymbol(). If the symbol was declare in the mapfile, the writeSymbol
function save the symbol in the new mapfile.