Add quadractic and cubic Bezier curves to custom symbols language

[joa-quim]

As title says. The idea is to be able to convert SVG images, that use a lot of Bezier curves, into GMT custom symbols. I'm labeling this as WIP because I have this locally for some time and forgot the details and code starts to rotten

Assisted-by: Claude Sonnet4.6

[joa-quim]

The bezier_demo_cubic.sh test should produce this

[Esteban82]

The bezier_demo_cubic.sh test should produce this

It works for me. I got this figure. Sorry by the delay.

[joa-quim]

The images you have post lately all suffer from same issue, non visible.

https://private-user-images.githubusercontent.com/537321/593183065-a3cc5c85-f34c-42bc-ad61-dc74c537adfb.png?jwt=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJnaXRodWIuY29tIiwiYXVkIjoicmF3LmdpdGh1YnVzZXJjb250ZW50LmNvbSIsImtleSI6ImtleTUiLCJleHAiOjE3NzkxMTQyMjgsIm5iZiI6MTc3OTExMzkyOCwicGF0aCI6Ii81MzczMjEvNTkzMTgzMDY1LWEzY2M1Yzg1LWYzNGMtNDJiYy1hZDYxLWRjNzRjNTM3YWRmYi5wbmc_WC1BbXotQWxnb3JpdGhtPUFXUzQtSE1BQy1TSEEyNTYmWC1BbXotQ3JlZGVudGlhbD1BS0lBVkNPRFlMU0E1M1BRSzRaQSUyRjIwMjYwNTE4JTJGdXMtZWFzdC0xJTJGczMlMkZhd3M0X3JlcXVlc3QmWC1BbXotRGF0ZT0yMDI2MDUxOFQxNDE4NDhaJlgtQW16LUV4cGlyZXM9MzAwJlgtQW16LVNpZ25hdHVyZT1lODgyMTkwMzRmNTU2NzQ2YWU3NjMzYjc1YTRlNzVjNGJlM2RhNzVlZTE4ZDVmNjBmMWVlZWZiZGE2OTNiOTA5JlgtQW16LVNpZ25lZEhlYWRlcnM9aG9zdCZyZXNwb25zZS1jb250ZW50LXR5cGU9aW1hZ2UlMkZwbmcifQ.1-HfS1Xb7C_zMMmk-62B5TmgJXs7BJf_3852TSCIlf0

[Esteban82]

The images you have post lately all suffer from same issue, non visible.

I didn't add any new image. I just cited the already post image. In my side looks fine.

[joa-quim]

Hmm, I see a 404

[seisman]

The test/psxy/bezier_demo_quadratic.sh fails because qbezier_test.def doesn't exist:

+ ctest --output-on-failure --force-new-ctest-process -j4 --timeout 480 --rerun-failed
Test project /home/runner/work/gmt/gmt/build
    Start 1034: test/psxy/bezier_demo_quadratic.sh
1/1 Test #1034: test/psxy/bezier_demo_quadratic.sh ...***Failed    0.73 sec
Set GMT_SESSION_NAME = 80226
Error: RROR]: Could not find either custom symbol or EPS macro qbezier_test
Error: RROR]: Option -S: Parsing failure
ERROR: gmtest:90
memtrack errors: 0
exit status: 1
ERROR: bezier_demo_quadratic.sh:20
memtrack errors: 0
exit status: 1

[joa-quim]

Ok, added it directly on master (by mistake)

[seisman]

The name qbezier_test.def is confusing. If it's only for testing purpose, it should not be added to share/custom.