Variant support slows us down by 10-50$. I assume most people will run
with `en` and so most of this overhead is to waste. So instead of
merging vars with dict, let's instead get a quick win by just skipping
vars when we don't need to. If the assumptions behind this change over
time or if there is need for speeding up a specific locale, we can
re-address this.
Before:
```
check_file/Typos/code time: [35.860 us 36.021 us 36.187 us]
thrpt: [8.0117 MiB/s 8.0486 MiB/s 8.0846 MiB/s]
check_file/Typos/corpus time: [26.966 ms 27.215 ms 27.521 ms]
thrpt: [21.127 MiB/s 21.365 MiB/s 21.562 MiB/s]
```
After:
```
check_file/Typos/code time: [33.837 us 33.928 us 34.031 us]
thrpt: [8.5191 MiB/s 8.5452 MiB/s 8.5680 MiB/s]
check_file/Typos/corpus time: [17.521 ms 17.620 ms 17.730 ms]
thrpt: [32.794 MiB/s 32.999 MiB/s 33.184 MiB/s]
```
This puts us inline with `--no-default-features --features dict`
Fixes#253
Bypass hashing when we know (through str::len) that a word won't be in
the dict.
Master:
```
real 0m26.675s
user 0m33.683s
sys 0m4.535s
```
With this change
```
real 0m24.432s
user 0m32.492s
sys 0m4.190s
```
The goal is to be as accepting and unobtrusive to new code bases as
possible. To this end, we correct typos into the closest english
dialect.
If someone wants to opt-in, they can have typos correct to a specific
english dialect.
Fixes#52Fixes#22
