experimental multitouch based smooth scrolling

high-resolution mouse wheels aren't supported in userland yet, so why
don't we fake a high resolution touchpad instead 😄

it's somewhat working, though it seems to crash on startup when
installed (among other weird bugs).

Cargo.lock

@@ -71,6 +71,12 @@ version = "0.1.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
 
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
 [[package]]
 name = "chrono"
 version = "0.4.19"
@@ -84,6 +90,15 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "cloudabi"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4344512281c643ae7638bbabc3af17a11307803ec8f0fcad9fae512a8bf36467"
+dependencies = [
+ "bitflags 1.2.1",
+]
+
 [[package]]
 name = "constant_time_eq"
 version = "0.1.5"
@@ -97,7 +112,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c3c7c73a2d1e9fc0886a08b93e98eb643461230d5f1925e4036204d5f2e261a8"
 dependencies = [
  "autocfg",
- "cfg-if",
+ "cfg-if 0.1.10",
  "lazy_static",
 ]
 
@@ -169,7 +184,7 @@ version = "0.1.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fc587bc0ec293155d5bfa6b9891ec18a1e330c234f896ea47fbada4cadbe47e6"
 dependencies = [
- "cfg-if",
+ "cfg-if 0.1.10",
  "libc",
  "wasi 0.9.0+wasi-snapshot-preview1",
 ]
@@ -185,6 +200,15 @@ dependencies = [
  "pkg-config",
 ]
 
+[[package]]
+name = "instant"
+version = "0.1.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cb1fc4429a33e1f80d41dc9fea4d108a88bec1de8053878898ae448a0b52f613"
+dependencies = [
+ "cfg-if 1.0.0",
+]
+
 [[package]]
 name = "lazy_static"
 version = "1.4.0"
@@ -206,13 +230,22 @@ dependencies = [
  "pkg-config",
 ]
 
+[[package]]
+name = "lock_api"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "28247cc5a5be2f05fbcd76dd0cf2c7d3b5400cb978a28042abcd4fa0b3f8261c"
+dependencies = [
+ "scopeguard",
+]
+
 [[package]]
 name = "log"
 version = "0.4.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4fabed175da42fed1fa0746b0ea71f412aa9d35e76e95e59b192c64b9dc2bf8b"
 dependencies = [
- "cfg-if",
+ "cfg-if 0.1.10",
 ]
 
 [[package]]
@@ -295,6 +328,32 @@ dependencies = [
  "objc",
 ]
 
+[[package]]
+name = "parking_lot"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a4893845fa2ca272e647da5d0e46660a314ead9c2fdd9a883aabc32e481a8733"
+dependencies = [
+ "instant",
+ "lock_api",
+ "parking_lot_core",
+]
+
+[[package]]
+name = "parking_lot_core"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c361aa727dd08437f2f1447be8b59a33b0edd15e0fcee698f935613d9efbca9b"
+dependencies = [
+ "cfg-if 0.1.10",
+ "cloudabi",
+ "instant",
+ "libc",
+ "redox_syscall",
+ "smallvec",
+ "winapi",
+]
+
 [[package]]
 name = "pkg-config"
 version = "0.3.19"
@@ -336,6 +395,12 @@ dependencies = [
  "crossbeam-utils",
 ]
 
+[[package]]
+name = "scopeguard"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
+
 [[package]]
 name = "signal-hook"
 version = "0.1.16"
@@ -356,6 +421,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "smallvec"
+version = "1.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fbee7696b84bbf3d89a1c2eccff0850e3047ed46bfcd2e92c29a2d074d57e252"
+
 [[package]]
 name = "strum"
 version = "0.8.0"
@@ -379,7 +450,9 @@ dependencies = [
  "directories",
  "evdev-rs",
  "hidapi",
+ "lazy_static",
  "notify-rust",
+ "parking_lot",
  "signal-hook",
 ]