This commit enables cpu, mem, block, and mutex profling of the FZF
executable. To support flushing the profiles at program exit it adds
util.AtExit to register "at exit" functions and mandates that util.Exit
is used instead of os.Exit to stop the program.
Co-authored-by: Junegunn Choi <junegunn.c@gmail.com>
This commit speeds up the parsing/processing of ANSI escape codes by
roughly 7.5x. The speedup is mostly accomplished by replacing the regex
with dedicated parsing logic (nextAnsiEscapeSequence()) and reducing the
number of allocations in extractColor().
#### Benchmarks
```
name old time/op new time/op delta
ExtractColor-16 4.89µs ± 5% 0.64µs ± 2% -86.87% (p=0.000 n=9+9)
name old speed new speed delta
ExtractColor-16 25.6MB/s ± 5% 194.6MB/s ± 2% +661.43% (p=0.000 n=9+9)
name old alloc/op new alloc/op delta
ExtractColor-16 1.37kB ± 0% 0.31kB ± 0% -77.31% (p=0.000 n=10+10)
name old allocs/op new allocs/op delta
ExtractColor-16 48.0 ± 0% 4.0 ± 0% -91.67% (p=0.000 n=10+10)
```
