1) enable static data use in the DLL:

FAILED linkandpostlink for armv6_urel: epoc32\release\armv6\urel\minehunt.dll
mmp: demos\declarative\minehunt\minehunt_0xE1601d5f.mmp
elf2e32 : Error: E1027: ELF File C:/S60/devices/g_s60_50/epoc32/release/armv6/urel/minehunt.dll.sym contains initialized writable data.

That error is a Symbian'ism - to use static data in DLLs, you must declare it explicitly in the project file
The cost of doing it automatically would be 4kB per DLL per process loading the DLL

In the .pro file, use:
symbian:TARGET.EPOCALLOWDLLDATA=1

2) write DEPLOYMENT section in the .pro file to enable the plugin to be installed on the phone