unable to set plot title

Bug category

[ ] bug - compilation error
[ ] bug - compilation warning
[ ] bug - runtime error
[ x] bug - runtime warning
[ ] bug - logic error

Describe the bug

When setting the title of a figure I get the following output at my terminal:

gnuplot> set multiplot title "{/:Bold My experiment}" font 'Arial,56' textcolor 'black'
                                                                      ^
         line 0: only valid in the context of an auto-layout command

gnuplot> set multiplot title "{/:Bold My experiment}" font 'Arial,56' textcolor 'black'
                                                                      ^
         line 0: only valid in the context of an auto-layout command

and no title is displayed in figure. Steps to Reproduce

Happens when I build the second example code here (as well as my own code): https://alandefreitas.github.io/matplotplusplus/appearance/figure-object/

Library is pulled into my project via CMake FetchContent. Library builds fine although I tend to compile with pretty high warnings (-Wall -Wextra -pedantic -Wcast-align -Wshadow) and the -Wshadow produces a lot of warnings...separate issue.

Platform

[ x] cross-platform issue - linux
[ ] cross-platform issue - windows
[ ] cross-platform issue - macos

Environment Details:

OS: Ubuntu 18.04 docker development container running on a Ubuntu 20.04 host
Compiler: g++ 7.5
gnuplot 5.2 patchlevel 2

alandefreitas / matplotplusplus

unable to set plot title #312