Enhancement: Additionl themes

[lucamosca1]

While checking around between forks and themes I found this ones attached. Unluckily I forgot to take notes about the original author but I'll leave here in case the maintainer wants to add them and in case correct credits in the future.

jiangnan_ink.json
sakura.json
soviet.json

[PasikVN]

any output sample ? ;)

[lucamosca1]

Done, resized a little

[lucamosca1]

While checking various forks for additional themes, I found this variation https://github.com/dimartarmizi/map-to-poster as a web application. Looking at code I found additional themes that I grab, fixed gradient color as background and tested. Ther could be some similarity to actual ones but I'll leave them here so that are available for everyone.
Some themes (cyber_noir and ancient_woodland) have been duplicated to match motorways color to primary roads since in my tests there are a few motorways and they doesn't look very good in original color. Up to author about which theme to include.
Enjoy

riverine_flow.json
royal_velvet.json
rustic_clay.json
sakura.json
sakura_bloom.json
solar_flare.json
steel_metropolis.json
sunset_blush.json
volcanic_ash.json
ancient_woodland.json
ancient_woodland_no_motorways.json
arctic_frost.json
arid_canyon.json
aurora_glow.json
autumn_whisper.json
blueprint_classic.json
charcoal_sketch.json
cyber_glitch.json
cyber_noir.json
cyber_noir_2.json
dark_gold.json
deep_ocean.json
desert_mirage.json
emerald_valley.json
ethereal_ghost.json
forest_shadow.json
golden_era.json
lavender_mist.json
mangrove_maze.json
midnight_neon.json
mint_fizz.json
monochrome_pro.json
night_drive.json
paper_heritage.json
retro_synth.json

[lucamosca1]

And their output