
Riding horses sometimes annoys you? Wait, what do you mean by "No"?
Well, then this mods adds horse improvements you haven't thought you needed.
Features:
Fastest Lead In the West
When mounted, clicking on a fence will leash the horse to it. Requires Lead in the special slot that's added to horse inventory.
When the leash is removed or broken - Lead will not drop and will remain in the slot.
How it looks:
Sink Rate, Pull Up!
Ridden horses can swim now. Press jump (spacebar) when in water.
Camels, Skeleton and Zombie horses are exceptions, by default. Configurable with '#horseman:cannot_swim' entity tag.
How it looks:
Get In a Boat and Set Course With a Horse
Horses now fit in boats.
How it looks:

What Are You Doing, Step-Height?
Increases horse step height by 10%. Allows riding up a path to a full block and not get stuck.
How it looks:
Experienced Miner
When mounted, your mining speed will remain the same as on ground. Removes 80% block break speed penalty when mounted.
How it looks:
Get Rotated, Horse
Keeps player's looking direction when mounting a horse. Rotates horse instead of you.
Look Around
When horse is not moving, player can move the camera independently of the ridden horse, up to 100 degrees (after which horse will follow the rotation).
Keep Your Speed
Reduces slowdown when riding down blocks (looks like opposite of step-up).
Keeps greater portion of horse's ground speed when airborne. Improves horizontal jump distance.
Moved Correctly
Fixes jitter and reset back when riding up blocks (especially stairs). Mojang bug: MC-100830
Patient Horse
Saddled horse will not go too far from where it was left by it's owner. Limits horse wandering distance.
Default radius is 16, to not make hitching obsolete.
Easy, Boy.
Prevents horse from rearing (stopping and standing on his hind legs) while mounted.
Magic Trick
Makes horse disappear (almost) when rider is looking down. Watch your step!
How it looks:
Inventory Switcheroo
Adds a button and a hotkey to switch between horse inventory and yours.
How it looks:

Heads Up (Display)
Improves GUI when mounted: Jumping meter will only show up when jumping; Makes hunger bar always visible;
How it looks:

Heads Down
Slightly improves visibility by lowering horse head position as well as rotating it forward.
Stop Killing Horses To Make Chests
Using Shears on a Donkey, Mule or Llama with a chest attached will remove the chest and drop it's contents.
Misc
- Fixes horizontal camera lag when mounted. MC-259512.
- Using saddle on a horse when in creative mode will instantly tame it.
- Jump meter will not fill up when swimming.
- Horses "jeb_" will become the rainbow.
Everything is, of horse, configurable.
Did you know that Donkeys, Mules, Llamas and Camels are Abstract Horses?
At least they a considered as such in Minecraft's code.
That means that most of the features of Horseman are applicable to these creatures as well.
Some of the features in Horseman are ported or adapted from the mod Horse Buff.
Author of Horse Buff is stopping development on it, and asked me if I want to include their features in my mod.
Enjoying the mod? Your support would be greatly appreciated!
External resources
Project members
mortuusars
Member