Rename all the plugins from <plugin-name>.c -> main.c

Just makes things more consistent.

src/splash-plugins/details/Makefile.am

@@ -11,6 +11,6 @@ details_la_CFLAGS = $(PLYMOUTH_CFLAGS)
 details_la_LDFLAGS = -module -avoid-version -export-dynamic
 details_la_LIBADD = $(PLYMOUTH_LIBS) ../../libply/libply.la
 details_la_SOURCES = $(srcdir)/../../ply-boot-splash-plugin.h         \
-                  $(srcdir)/details.c
+                     $(srcdir)/plugin.c
 
 MAINTAINERCLEANFILES = Makefile.in

src/splash-plugins/spinfinity/Makefile.am

@@ -15,7 +15,7 @@ spinfinity_la_SOURCES = $(srcdir)/../../ply-boot-splash-plugin.h             \
                             $(srcdir)/../../ply-window.c                     \
                             $(srcdir)/throbber.h                             \
                             $(srcdir)/throbber.c                             \
-                            $(srcdir)/spinfinity.c
+                            $(srcdir)/plugin.c
 
 throbber_frames =                                                            \
                     throbber-00.png                                          \

src/splash-plugins/text/Makefile.am

@@ -11,6 +11,6 @@ text_la_CFLAGS = $(PLYMOUTH_CFLAGS)
 text_la_LDFLAGS = -module -avoid-version -export-dynamic
 text_la_LIBADD = $(PLYMOUTH_LIBS) ../../libply/libply.la
 text_la_SOURCES = $(srcdir)/../../ply-boot-splash-plugin.h         \
-                  $(srcdir)/text.c
+                  $(srcdir)/plugin.c
 
 MAINTAINERCLEANFILES = Makefile.in