Implement option to delete snapshot

Requested in [gh##52]

lib/Bindings/CBindings.cpp

@@ -202,6 +202,18 @@ void tukit_free_sm_list(tukit_sm_list list) {
     delete result;
 }
 
+int tukit_sm_deletesnap(const char* id) {
+    try {
+        std::unique_ptr<TransactionalUpdate::SnapshotManager> snapshotMgr = TransactionalUpdate::SnapshotFactory::get();
+        snapshotMgr->deleteSnap(id);
+        return 0;
+    } catch (const std::exception &e) {
+        fprintf(stderr, "ERROR: %s\n", e.what());
+        errmsg = e.what();
+        return -1;
+    }
+}
+
 int tukit_reboot(const char* method) {
     try {
         auto rebootmgr = Reboot{method};

lib/Bindings/libtukit.h

@@ -41,6 +41,7 @@ typedef void* tukit_sm_list;
 tukit_sm_list tukit_sm_get_list(size_t* len, const char* columns);
 const char* tukit_sm_get_list_value(tukit_sm_list list, size_t row, size_t columns);
 void tukit_free_sm_list(tukit_sm_list list);
+int tukit_sm_deletesnap(const char* id);
 int tukit_reboot(const char* method);
 
 #ifdef __cplusplus

lib/Snapshot/Snapper.cpp

@@ -118,6 +118,10 @@ std::string Snapper::getDefault() {
     return match[1].str();
 }
 
+void Snapper::deleteSnap(std::string id) {
+    callSnapper("delete " + id);
+}
+
 bool Snapper::isInProgress() {
     std::string desc = callSnapper("--csvout list --columns number,userdata");
     std::smatch match;

lib/Snapshot/Snapper.hpp

@@ -35,6 +35,7 @@ class Snapper: public SnapshotManager, public Snapshot {
     std::deque<std::map<std::string, std::string>> getList(std::string columns) override;
     std::string getCurrent() override;
     std::string getDefault() override;
+    void deleteSnap(std::string id) override;
 private:
     std::string callSnapper(std::string);
     inline static bool snapperNoDbus;

lib/SnapshotManager.hpp

@@ -29,6 +29,7 @@ class SnapshotManager
     virtual std::deque<std::map<std::string, std::string>> getList(std::string columns) = 0;
     virtual std::string getCurrent() = 0;
     virtual std::string getDefault() = 0;
+    virtual void deleteSnap(std::string id) = 0;
 };
 
 class SnapshotFactory {

lib/Transaction.hpp

@@ -78,6 +78,7 @@ class Transaction {
     /**
      * @brief Execute the given application in the new snapshot
      * @param argv
+     * @param (optional) output Variable to store the command's output to
      * @return application's return code
      *
      * Execute any given command within the new snapshot. The application's output will be
@@ -92,6 +93,7 @@ class Transaction {
     /**
      * @brief Replace '{}' in argv with mount directory and execute command
      * @param argv
+     * @param (optional) output Variable to store the command's output to
      * @return application's return code
      *
      * Replace any standalone occurrence of '{}' in argv with the snapshot's mount directory