spellcheck: Use <> to include Geany headers

[b4n]

Apparently some older versions of cppcheck get stupid when passed extra
flags like -D, so try and make them happy by showing them those are
library (system-wide) headers rather than application (local) ones.

[b4n]

Err, there's a typo in the plugin's name, funny for a spellcheck-related fix :)

[b4n]

fixed the typo

[eht16]

I'm happy with merging this.
Still being curious: where is the typo you mentioned? In the diff? In the title of this PR, then it is not fixed :).

And more related to the changes themselves: shouldn't other plugins which use #include "geanyplugin.h" also be affected? Or is there something special in SpellCheck from cppcheck's POV?

[b4n]

Still being curious: where is the typo you mentioned? In the diff? In the title of this PR, then it is not fixed :).

It was the commit message, but I forgot to update the title (which was autogenerated from the commit) :)

And more related to the changes themselves: shouldn't other plugins which use #include "geanyplugin.h" also be affected? Or is there something special in SpellCheck from cppcheck's POV?

Apparently other plugins are not affected, yet I can't really tell you why. All I can guess is that, as stated in the commit message, when you pass defines options to cppheck (-Dsomething) it starts requiring all "" headers to be found -- maybe it tries running a preprocessor or something in this case? As SpellCheck is the only plugin passing a -D option to cppcheck, it's the only one affected.