Add support for custom emotes

[zet4]

Fediverse servers such as Mastodon and Pleroma have support for adding custom emojis, currently the app does not support this and thus all the custom emojis just look like :text:.

For example this status: https://mstdn.io/users/zeta/statuses/99893603217308279
Is OK on Pleroma: https://stuff.zeta.pm/up/PowderbluePositivePacificparrotlet
And is OK on Mastodon: https://stuff.zeta.pm/up/WobblyWelllitIggypops
But is NOT OK on Flantter: https://stuff.zeta.pm/up/AmusingAdolescentAlligatorgar

[cucmberium]

I implemented a feature of showing custom emojis before.
But that version has a bug that client is terminated abnormally when enabling the setting "Enable tweet text selection".
The cause is unknown and I couldn't fix it. (See branch feature/custom_emoji)
I plan to implement about custom emoji using another approach.
Please wait a moment for next release.

[cucmberium]

reference : #124 #125

[LordMicroMan]

New user for Flantter. Don't have "Enable tweet text selection" on but still can't use custom mastodon emoji. Any news on the update?