key mappings for inputting

[ktr0731]

Problem

Evans uses c-bata/go-prompt as the input method in REPL mode.
c-bata/go-prompt doesn't return C-d (io.EOF), only returns empty string.
so, Evans cannot determine whether empty input is C-d or just entered.
therefore, currently, Evans doesn't use C-d to notify end of input.

Currently key mappings

mapping	result
enter	inputs default value (in repeated fields, this mapping is disabled.)
enter + enter	terminates inputting repeated fields

New key mappings for new features

I planning streaming modes.
for these features, I will introduce new key mappings to terminate stream.

mapping	result
C-c	terminates each streaming mode

also to fix behavior of enter mapping in repeated fields, I considering abolish enter + enter mapping.
instead of the mapping, C-c mapping terminates repeated fields inputting.

if you have any idea, please tell me.

thanks.

Note

the final mapping table is:

mapping	result
enter	inputs default value
C-c	terminates each mode (if current field is not repeated fields)
C-c	terminates inputting repeated fields

if you want to terminate streaming mode in repeated fields inputting, you need to input C-c two times.

[mitramejia]

I had to go to the issues to know the keymap to end repeating inputs, it would be good to move this to README