Improve comprehensibility and consistency of window placement mode names

Summary:
Right now a few of the window placement modes suffer one or more of the following problems:
- Inconsistency between the text shown in the Window Behavior and Window Rules KCMs
- Title does not indicate what it does
- Awkward wording
- Lack of unity in grammatical mood between the different modes

This patch fixes these issues by improving the strings and standardizing on the descriptive mood:
- Smart -> Minimal Overlapping
- Maximizing -> Maximized
- Cascade -> Cascaded
- Zero-Cornered -> In Top-Left Corner

Strings are also unified between the window behavior and window rules KCMs, and docbooks are adjusted accordingly.

Test Plan:
{F7279685, size=full}
{F7279694, size=full}

Reviewers: #kwin, #vdg, ndavis, filipf, zzag, romangg

Reviewed By: #kwin, #vdg, ndavis, filipf, romangg

Subscribers: gladhorn, alexeymin, IlyaBizyaev, broulik, hein, hpereiradacosta, GB_2, alexde, davidedmundson, romangg, cfeck, filipf, zzag, ndavis, kwin, kde-doc-english

Tags: #kwin, #documentation

Differential Revision: https://phabricator.kde.org/D23415

doc/windowbehaviour/index.docbook

@@ -642,11 +642,11 @@ the spinbox to configure the delay un-shading.
 <varlistentry>
 <term><guilabel>Placement</guilabel></term>
 <listitem><para>The placement policy determines where a new window will appear
-on the desktop.  <guilabel>Smart</guilabel> will try to achieve a minimum
+on the desktop.  <guilabel>Minimal Overlapping</guilabel> will try to achieve a minimum
-overlap of windows, <guilabel>Cascade</guilabel> will cascade the
+overlap of windows, <guilabel>Cascaded</guilabel> will cascade the
 windows, and <guilabel>Random</guilabel> will use a random
 position.  <guilabel>Centered</guilabel> will open all new windows in
-the center of the screen, and <guilabel>Zero-Cornered</guilabel> will
+the center of the screen, and <guilabel>In Top-Left Corner</guilabel> will
 open all windows with their top left corner in the top left corner of
 the screen.</para></listitem>
 </varlistentry>

doc/windowspecific/index.docbook

@@ -338,12 +338,12 @@ and <guibutton>Move Down</guibutton> buttons effects on how they are applied.</p
 <itemizedlist>
 <listitem><para><guilabel>Default</guilabel> - use the global window placement strategy.</para></listitem>
 <listitem><para><guilabel>No Placement</guilabel> - top-left corner.</para></listitem>
-<listitem><para><guilabel>Smart</guilabel> - place where no other window exists.</para></listitem>
+<listitem><para><guilabel>Minimal Overlapping</guilabel> - place where no other window exists.</para></listitem>
-<listitem><para><guilabel>Maximizing</guilabel> - start the window maximized.</para></listitem>
+<listitem><para><guilabel>Maximized</guilabel> - start the window maximized.</para></listitem>
-<listitem><para><guilabel>Cascade</guilabel> - staircase-by-title.</para></listitem>
+<listitem><para><guilabel>Cascaded</guilabel> - staircase-by-title.</para></listitem>
 <listitem><para><guilabel>Centered</guilabel> - center of the desktop.</para></listitem>
 <listitem><para><guilabel>Random</guilabel></para></listitem>
-<listitem><para><guilabel>Top-Left Corner</guilabel></para></listitem>
+<listitem><para><guilabel>In Top-Left Corner</guilabel></para></listitem>
 <listitem><para><guilabel>Under Mouse</guilabel></para></listitem>
 <listitem><para><guilabel>On Main Window</guilabel> - restrict placement of a child window to the boundaries of the parent window.</para></listitem>
 </itemizedlist>

kcmkwin/kwinoptions/advanced.ui

@@ -77,17 +77,17 @@
      </property>
      <item>
       <property name="text">
-       <string>Smart</string>
+       <string>Minimal Overlapping</string>
       </property>
      </item>
      <item>
       <property name="text">
-       <string>Maximizing</string>
+       <string>Maximized</string>
       </property>
      </item>
      <item>
       <property name="text">
-       <string>Cascade</string>
+       <string>Cascaded</string>
       </property>
      </item>
      <item>
@@ -102,7 +102,7 @@
      </item>
      <item>
       <property name="text">
-       <string>Zero-cornered</string>
+       <string>In Top-Left Corner</string>
       </property>
      </item>
      <item>

kcmkwin/kwinrules/ruleswidgetbase.ui

@@ -1063,17 +1063,17 @@
          </item>
          <item>
           <property name="text">
-           <string>Smart</string>
+           <string>Minimal Overlapping</string>
           </property>
          </item>
          <item>
           <property name="text">
-           <string>Maximizing</string>
+           <string>Maximized</string>
           </property>
          </item>
          <item>
           <property name="text">
-           <string>Cascade</string>
+           <string>Cascaded</string>
           </property>
          </item>
          <item>
@@ -1088,7 +1088,7 @@
          </item>
          <item>
           <property name="text">
-           <string>Top-Left Corner</string>
+           <string>In Top-Left Corner</string>
           </property>
          </item>
          <item>