graphics/xpaint: Update to 3.1.4

• Switch to DISTVERSION
• Define LICENSE_FILE
• Use autoreconf as workaround to fix build (not needed in <= 3.1.3)
• Put most SED commands in patches
• Comment patches about what they doing
• Port uses USES=jpeg and not openjpeg* (at the moment)
• Take maintainership

ChangeLog: https://sourceforge.net/projects/sf-xpaint/files/sf-xpaint/