Improve spacing of math italic j and i

Change the terminal ball of the j or require smaller left side bearing,
and also increase the right side bearing of the i a bit.

Fixes #273

sources/LibertinusMath-Regular.sfd

@@ -116375,10 +116375,9 @@ EndChar
 
 StartChar: u1D456
 Encoding: 119894 119894 2798
-Width: 189
+Width: 229
 GlyphClass: 2
 Flags: MW
-ItalicCorrection: 41
 TopAccentHorizontal: 166
 LayerCount: 2
 Fore
@@ -116389,26 +116388,26 @@ SplineSet
  210 544 188 522 162 522 c 0
  136 522 114 544 114 570 c 0
 EndSplineSet
-Refer: 3244 120484 N 1 0 0 1 0 0 2
+Refer: 3244 120484 N 1 0 0 1 0 0 3
 EndChar
 
 StartChar: u1D457
 Encoding: 119895 119895 2799
-Width: 357
+Width: 267
 GlyphClass: 2
 Flags: MW
 ItalicCorrection: 63
-TopAccentHorizontal: 357
+TopAccentHorizontal: 267
 LayerCount: 2
 Fore
 SplineSet
-304 570 m 0
- 304 596 326 618 352 618 c 0
- 378 618 400 596 400 570 c 0
- 400 544 378 522 352 522 c 0
- 326 522 304 544 304 570 c 0
+214 570 m 0
+ 214 596 236 618 262 618 c 0
+ 288 618 310 596 310 570 c 0
+ 310 544 288 522 262 522 c 0
+ 236 522 214 544 214 570 c 0
 EndSplineSet
-Refer: 3245 120485 N 1 0 0 1 -0.3 0 2
+Refer: 3245 120485 N 1 0 0 1 0 0 3
 EndChar
 
 StartChar: u1D458
@@ -132120,10 +132119,9 @@ EndChar
 
 StartChar: u1D6A4
 Encoding: 120484 120484 3244
-Width: 179
+Width: 229
 GlyphClass: 2
 Flags: MW
-ItalicCorrection: 41
 TopAccentHorizontal: 121
 LayerCount: 2
 Fore
@@ -132150,30 +132148,50 @@ EndChar
 
 StartChar: u1D6A5
 Encoding: 120485 120485 3245
-Width: 326
+Width: 267
 GlyphClass: 2
 Flags: MW
 ItalicCorrection: 63
-TopAccentHorizontal: 309
+TopAccentHorizontal: 219
 LayerCount: 2
-Fore
+Back
 SplineSet
-349.6 320.2 m 2
- 331.3 234 l 2
- 279.8 -9.1 227.3 -196 102.3 -196 c 0
- 58.3 -196 20.3 -180 20.3 -148 c 0
- 20.3 -126.9 36.1 -117 49.3 -117 c 0
- 98.6 -117 93.1 -160 120.3 -160 c 0
- 138.3 -160 172.3 -142 194.3 -56 c 0
- 212.6 15.5 221.8 78.5 243.3 176 c 2
- 275.3 321 l 2
- 281.3 349 283.3 362.9 283.3 372 c 0
- 283.3 382 277.3 391 265.3 392 c 2
- 225.3 395 l 1
- 219.3 404 217.6 415 224.3 423 c 1
- 271.3 430 316.3 436 348.3 436 c 0
- 361.5 436 368.8 428.6 368.8 414.9 c 0
- 368.8 402 358.3 360 349.6 320.2 c 2
+260 320 m 2
+ 241 234 l 2
+ 189 -9 137 -196 12 -196 c 0
+ -32 -196 -70 -180 -70 -148 c 0
+ -70 -127 -54 -117 -41 -117 c 0
+ 8 -117 3 -160 30 -160 c 0
+ 48 -160 82 -142 104 -56 c 0
+ 122 16 131 78 153 176 c 2
+ 185 321 l 2
+ 191 349 193 363 193 372 c 0
+ 193 382 187 391 175 392 c 2
+ 135 395 l 1
+ 129 404 127 415 134 423 c 1
+ 181 430 226 436 258 436 c 0
+ 271 436 279 429 279 415 c 0
+ 279 402 269 360 260 320 c 2
+EndSplineSet
+Fore
+SplineSet
+260 320 m 2
+ 241 234 l 2
+ 189 -9 139 -177 35 -192 c 0
+ -4 -197 -32 -175 -34 -134 c 0
+ -35 -113 -23 -95 -6 -95 c 0
+ 9 -95 30 -104 19 -145 c 0
+ 15 -161 30 -164 38 -163 c 0
+ 54 -161 82 -142 104 -56 c 0
+ 122 16 131 79 153 176 c 2
+ 185 321 l 2
+ 191 349 193 363 193 372 c 0
+ 193 382 187 391 175 392 c 2
+ 135 395 l 1
+ 129 404 127 415 134 423 c 1
+ 181 430 226 436 258 436 c 0
+ 271 436 279 429 279 415 c 0
+ 279 402 268 360 260 320 c 2
 EndSplineSet
 EndChar