Improve rendering of superscript in plain output.

We now handle a few non digit characters (+, -, =, parentheses)
for which there are superscripted unicode characters.

Closes #3518.

1 files changed, 6 insertions, 0 deletions

diff --git a/test/command/3518.md b/test/command/3518.md
new file mode 100644
index 000000000..ec3322192
--- /dev/null
+++ b/test/command/3518.md
@@ -0,0 +1,6 @@
+```
+pandoc -f latex -t plain
+$\alpha^2 \cdot \alpha^{2+3} \equiv \alpha^7$
+^D
+α² ⋅ α² ⁺ ³ ≡ α⁷
+```