fix that researched tech can be picked when we pick a free tech (#1049)

* systemProp

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* fix that researched tech can be picked when we pick a free tech

* update to master

* update

* Update TechPickerScreen.kt

android/assets/jsons/Translations/Buildings.json

@@ -298,7 +298,7 @@
 		German:"Kostenloser Solzialgrundsatz"
 		Dutch:"Gratis sociaalbeleid"
 		Spanish:"Política social gratis"
-		Simplified_Chinese:"获得1次免费推行社会政策的机会"
+		Simplified_Chinese:"可免费推行1项社会政策"
 		Portuguese:"Politica social gratis"
 		Polish:"Darmowy ustrój społeczny"
 	}

core/src/com/unciv/ui/pickerscreens/TechPickerScreen.kt

@@ -125,9 +125,10 @@ class TechPickerScreen(internal val civInfo: CivilizationInfo, centerOnTech: Tec
                 civTech.isResearched(techName) && techName!="Future Tech" -> techButton.color = researchedTechColor
                 tempTechsToResearch.isNotEmpty() && tempTechsToResearch.first() == techName -> techButton.color = currentTechColor
                 tempTechsToResearch.contains(techName) -> techButton.color = queuedTechColor
-                researchableTechs.contains(techName) -> techButton.color = researchableTechColor
                 else -> techButton.color = Color.BLACK
             }
+            //the tech that can be selected to research immediately should be always researchableTechColor, it's very good when we pick a free tech.
+            if (researchableTechs.contains(techName)&&!civTech.isResearched(techName)) techButton.color = researchableTechColor
 
             var text = techName.tr()
 
@@ -161,6 +162,7 @@ class TechPickerScreen(internal val civInfo: CivilizationInfo, centerOnTech: Tec
 
         if (isFreeTechPick) {
             selectTechnologyForFreeTech(tech)
+            setButtonsInfo()
             return
         }
 
@@ -189,7 +191,7 @@ class TechPickerScreen(internal val civInfo: CivilizationInfo, centerOnTech: Tec
 
 
     private fun selectTechnologyForFreeTech(tech: Technology) {
-        if (researchableTechs.contains(tech.name)) {
+        if (researchableTechs.contains(tech.name)&&!civTech.isResearched(tech.name)) {
             pick("Pick [${selectedTech!!.name}] as free tech".tr())
         } else {
             rightSideButton.setText("Pick a free tech".tr())