New icons added for Plot2d. They was forgotten in 1.2 version

diff --git a/resources/plot2d_curves_settings.png b/resources/plot2d_curves_settings.png
new file mode 100755 (executable)
index 0000000..53d4f2c
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diff --git a/resources/plot2d_minus.png b/resources/plot2d_minus.png
new file mode 100755 (executable)
index 0000000..055182e
Binary files /dev/null and b/resources/plot2d_minus.png differ