Strict mode for BlockStateMask.

When true, it will only match blocks that have the desired properties.
When false, it will only fail blocks that have the properties but incorrect values.

worldedit-core/src/main/java/com/sk89q/worldedit/EditSession.java

@@ -1308,7 +1308,7 @@ public int drainArea(BlockVector3 origin, double radius, boolean waterlogged) th
                                 getWorld().createLiquidMask(),
                                 new BlockStateMask(this, new HashMap<String, String>() {{
                                     put("waterlogged", "true");
-                                }}))
+                                }}, true))
                             : getWorld().createLiquidMask());
 
         BlockReplace replace;

worldedit-core/src/main/java/com/sk89q/worldedit/extension/factory/parser/mask/BlockStateMaskParser.java

@@ -43,15 +43,16 @@ public BlockStateMaskParser(WorldEdit worldEdit) {
 
     @Override
     public Mask parseFromInput(String input, ParserContext context) throws InputParseException {
-        if (!input.startsWith("^[") || !input.endsWith("]")) {
+        if (!(input.startsWith("^[") || input.startsWith("^=[")) || !input.endsWith("]")) {
             return null;
         }
         Extent extent = Request.request().getEditSession();
-
-        String states = input.substring(2, input.length() - 1);
+        boolean strict = input.charAt(1) == '=';
+        String states = input.substring(2 + (strict ? 1 : 0), input.length() - 1);
         try {
             return new BlockStateMask(extent,
-                    Splitter.on(',').omitEmptyStrings().trimResults().withKeyValueSeparator('=').split(states));
+                    Splitter.on(',').omitEmptyStrings().trimResults().withKeyValueSeparator('=').split(states),
+                    strict);
         } catch (Exception e) {
             throw new InputParseException("Invalid states.", e);
         }

worldedit-core/src/main/java/com/sk89q/worldedit/function/mask/BlockStateMask.java

@@ -36,6 +36,14 @@ public class BlockStateMask extends AbstractExtentMask {
     private final boolean strict;
     private Map<BlockType, Map<Property<Object>, Object>> cache = Maps.newHashMap();
 
+    /**
+     * Creates a mask that checks if a given block has the desired properties set to the desired value.
+     *
+     * @param extent the extent to get blocks from
+     * @param states the desired states (property -> value) that a block should have to match the mask
+     * @param strict true to only match blocks that have all properties and values, false to also match blocks that
+     *              do not have the properties (but only fail blocks with the properties but wrong values)
+     */
     public BlockStateMask(Extent extent, Map<String, String> states, boolean strict) {
         super(extent);
         this.states = states;