Clean up histogram code

Author: jchristopherson

examples/histogram_example.f90

@@ -28,7 +28,6 @@ program example
     ! Plot the data
     call pd1%set_bin_count(nbins)   ! optional, but must be done prior to define_data is used
     call pd1%define_data(x)
-    call pd1%set_transparency(0.5)  ! optional - for illustration purposes
     call plt%push(pd1)
     call plt%draw()
 end program

src/CMakeLists.txt

@@ -42,6 +42,5 @@ set(FPLOT_SOURCES
     ${dir}/fplot_plot_data_3d.f90
     ${dir}/fplot_surface_plot_data.f90
     ${dir}/fplot_stats_plots.f90
-    ${dir}/fplot_plot_histogram.f90
 )
 set(FPLOT_SOURCES ${FPLOT_SOURCES} PARENT_SCOPE)