Not all unicode characters are valid Gujarati characters. ```UnsupportedGU``` is never thrown

[samyakbhuta]

Have a look at https://github.com/samyakbhuta/gtts/blob/master/project/ss/lang/gu/GujCharSupport.java#L26.

Hardcoded, always false condition is inappropriate. The correct behavior is to check for Gujarati unicode character for validity. Commented out code on the same line is meant to do the same and it shall be used.

Currently, even non-Gujarati unicode characters are passing through method public static boolean isValidGujChar(char ch) throws UnsupportedGU. Due to that system is throwing following exception elsewhere.

Exception in thread "AWT-EventQueue-0" java.lang.StringIndexOutOfBoundsException: String index out of range: -1
    at java.lang.AbstractStringBuilder.replace(AbstractStringBuilder.java:789)
    at java.lang.StringBuffer.replace(StringBuffer.java:387)
    at project.ss.lang.gu.ipatrans.FileName.getString(FileName.java:154)
    at project.ss.lang.gu.ipatrans.NewEditor.getFinalString(NewEditor.java:77)
    at project.ss.lang.gu.ipatrans.ToIPATranscriptorImpl.transcriptToIPA(ToIPATranscriptorImpl.java:41)
    at project.ss.SynthesizerImpl.speak(SynthesizerImpl.java:171)
    at project.ss.SynthesizerImpl.speak(SynthesizerImpl.java:167)
    at project.gui.JTTSFrame.actionPerformed(JTTSFrame.java:268)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener$Actions.actionPerformed(BasicButtonListener.java:303)
    at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1664)
    at javax.swing.JComponent.processKeyBinding(JComponent.java:2879)
    at javax.swing.JComponent.processKeyBindings(JComponent.java:2926)
    at javax.swing.JComponent.processKeyEvent(JComponent.java:2842)
    at java.awt.Component.processEvent(Component.java:6282)
    at java.awt.Container.processEvent(Container.java:2229)
    at java.awt.Component.dispatchEventImpl(Component.java:4861)
    at java.awt.Container.dispatchEventImpl(Container.java:2287)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1895)
    at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:762)
    at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:1027)
    at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:899)
    at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:727)
    at java.awt.Component.dispatchEventImpl(Component.java:4731)
    at java.awt.Container.dispatchEventImpl(Container.java:2287)
    at java.awt.Window.dispatchEventImpl(Window.java:2719)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:729)
    at java.awt.EventQueue.access$200(EventQueue.java:103)
    at java.awt.EventQueue$3.run(EventQueue.java:688)
    at java.awt.EventQueue$3.run(EventQueue.java:686)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
    at java.awt.EventQueue$4.run(EventQueue.java:702)
    at java.awt.EventQueue$4.run(EventQueue.java:700)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:699)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)