plot_tissue: Plot the tissue slide showing the FITC intensity
In Kevin-Haigis-Lab/PackageBluishgreen: Classify cells by fluorescence

Plots the slide with each point representing a cell and the color represents the intensity of FITC.

plot_tissue(
  ts,
  color,
  prop = 0.25,
  point_size = 0.5,
  point_alpha = 0.8,
  color_pal = "RdYlBu"
)

`ts`	Tissue slide object to plot.
`color`	The column to use for coloring each cell. (enquoted)
`prop`	The proportion of cells to plot (too many cells can slow performance).
`point_size`	Size of each point.
`point_alpha`	Transparency of each point.
`color_pal`	A diverging color palette to be passed to `ggplot2::scale_color_distiller()`.