core: admin can remove contestant before contest start (#1196)

packages/hydrooj/locales/ko.yaml

@@ -685,6 +685,7 @@ The user is too lazy to leave something here...: 설명이 없습니다... (´
 There are no contests...: 대회 없음
 There is no homework so far ╰(*°▽°*)╯: 과제 없음 ╰(*°▽°*)╯
 This contest is not live.: 대회가 실시간이 아닙니다.
+This contest has already started.: 대회가 이미 시작되었습니다.
 This email was sent by {0} automatically, and please do not reply directly.: '{0}으로 이메일을 보냈습니다.'
 This homework is not open and you cannot view problems.: 과제를 열지 않았기에 문제를 볼 수 없습니다.
 This homework is not open.: 과제가 아직 닫혀 있습니다.

packages/hydrooj/locales/zh.yaml

@@ -811,6 +811,7 @@ theme: 主题
 There are no contests...: 没有比赛…
 There is no homework so far ╰(*°▽°*)╯: 目前还没有作业 ╰(*°▽°*)╯
 This contest is not live.: 比赛没有开始。
+This contest has already started.: 比赛已开始。
 This email was sent by {0} automatically, and please do not reply directly.: 这封邮件由 {0} 自动发送，请勿直接回复。
 This homework is not open and you cannot view problems.: 该作业还未到开放时间，您无法查看作业题目。
 This homework is not open.: 该作业还未开放递交。

packages/hydrooj/locales/zh_TW.yaml

@@ -808,6 +808,7 @@ theme: 主題
 There are no contests...: 沒有比賽…
 There is no homework so far ╰(*°▽°*)╯: 目前沒有功課 ╰(*°▽°*)╯
 This contest is not live.: 比賽沒有開始。
+This contest has already started.: 比賽已開始。
 This email was sent by {0} automatically, and please do not reply directly.: 這封郵件由 {0} 自動傳送，請勿直接回復。
 This homework is not open and you cannot view problems.: 功課尚未開放，不能檢視題目。
 This homework is not open.: 功課尚未開放遞交。