Reworked install / uninstall

Hardened scripts a little, made them more distro agnostic

scripts/fix-opera.sh

@@ -10,22 +10,22 @@ if [[ $(uname -m) != "x86_64" ]]; then
 	exit 1
 fi
 
-if ! which unzip > /dev/null; then
+if command -v unzip > /dev/null; then
 	printf '\033[1munzip\033[0m package must be installed to run this script\n'
 	exit 1
 fi
 
-if ! which curl > /dev/null; then
+if command -v curl > /dev/null; then
 	printf '\033[1mcurl\033[0m package must be installed to run this script\n'
 	exit 1
 fi
 
-if ! which jq > /dev/null; then
+if command -v jq > /dev/null; then
 	printf '\033[1mjq\033[0m package must be installed to run this script\n'
 	exit 1
 fi
 
-if which pacman &> /dev/null; then
+if command -v pacman &> /dev/null; then
 	ARCH_SYSTEM=true
 fi
 
@@ -136,4 +136,4 @@ done
 
 #Removing temporary files
 printf 'Removing temporary files...\n'
-rm -rf "$FIX_DIR"
+rm -rf "$FIX_DIR"