Fix linking with system wxsqlite3

wxsqlite3-3.0.5 $ grep -e Libs: wxsqlite3.pc.in
Libs: -L${libdir} -lwxcode_gtk2_wxsqlite3-@WXVERSION@
Merge pull request #8 from Nikoli/build_system

Fix linking with system wxsqlite3
Update wxWidgets version
Ubuntu 14.04
Detect file wxSQLite3Lib in ./configure
merge with master