remove Qt guards (#3328)

* remove version guards

* clangify

* [skip ci] README wording

* add cmake requirement to readme

* remove return

* remove min req from README

cockatrice/src/filterbuilder.cpp

@@ -26,9 +26,7 @@ FilterBuilder::FilterBuilder(QWidget *parent) : QWidget(parent)
     edit = new QLineEdit;
     edit->setObjectName("edit");
     edit->setPlaceholderText(tr("Type your filter here"));
-#if QT_VERSION >= 0x050200
     edit->setClearButtonEnabled(true);
-#endif
     edit->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Fixed);
 
     QGridLayout *layout = new QGridLayout;

cockatrice/src/logger.cpp

@@ -2,15 +2,12 @@
 #include "version_string.h"
 #include <QDateTime>
 #include <QLocale>
+#include <QSysInfo>
 #include <iostream>
 
 #define LOGGER_MAX_ENTRIES 128
 #define LOGGER_FILENAME "qdebug.txt"
 
-#if QT_VERSION >= 0x050400
-#include <QSysInfo>
-#endif
-
 Logger::Logger() : logToFileEnabled(false)
 {
     logBuffer.append(getClientVersion());
@@ -104,11 +101,7 @@ QString Logger::getSystemArchitecture()
 
 QString Logger::getClientOperatingSystem()
 {
-#if QT_VERSION >= 0x050400
     return QSysInfo::prettyProductName();
-#endif
-
-    return {};
 }
 
 QString Logger::getSystemLocale()

cockatrice/src/tab_deck_editor.cpp

@@ -345,12 +345,8 @@ void TabDeckEditor::createCentralFrame()
     searchEdit = new SearchLineEdit;
     searchEdit->setObjectName("searchEdit");
     searchEdit->setPlaceholderText(tr("Search by card name"));
-#if QT_VERSION >= 0x050200
     searchEdit->setClearButtonEnabled(true);
-#endif
-#if QT_VERSION >= 0x050300
     searchEdit->addAction(QPixmap("theme:icons/search"), QLineEdit::LeadingPosition);
-#endif
     searchEdit->installEventFilter(&searchKeySignals);
 
     setFocusProxy(searchEdit);