Fix some wording and grammar nits.

Doc/lib/libdecimal.tex

@@ -84,7 +84,7 @@ the decimal module are: \constant{Clamped}, \constant{InvalidOperation},
 \constant{Subnormal}, \constant{Overflow}, and \constant{Underflow}.
 
 For each signal there is a flag and a trap enabler.  When a signal is
-encountered, its flag incremented from zero and, then, if the trap enabler
+encountered, its flag is incremented from zero and, then, if the trap enabler
 is set to one, an exception is raised.  Flags are sticky, so the user
 needs to reset them before monitoring a calculation.
 
@@ -119,7 +119,7 @@ Context(prec=28, rounding=ROUND_HALF_EVEN, Emin=-999999999, Emax=999999999,
 \end{verbatim}
 
 
-Decimal instances can be constructed from integers, strings or tuples.  To
+Decimal instances can be constructed from integers, strings, or tuples.  To
 create a Decimal from a \class{float}, first convert it to a string.  This
 serves as an explicit reminder of the details of the conversion (including
 representation error).  Decimal numbers include special values such as
@@ -160,7 +160,7 @@ Decimal("5.85988")
 \end{verbatim}
 
 
-Decimals interact well with much of the rest of python.  Here is a small
+Decimals interact well with much of the rest of Python.  Here is a small
 decimal floating point flying circus:
     
 \begin{verbatim}    
@@ -741,7 +741,7 @@ exception is raised upon encountering the condition.
 \end{classdesc*}
 
 \begin{classdesc*}{DecimalException}
-    Base class for other signals and is a subclass of
+    Base class for other signals and a subclass of
     \exception{ArithmeticError}.
 \end{classdesc*}
 
@@ -847,7 +847,7 @@ distributive properties of addition:
 
 \begin{verbatim}
 # Examples from Seminumerical Algorithms, Section 4.2.2.
->>> from decimal import *
+>>> from decimal import Decimal, getcontext
 >>> getcontext().prec = 8
 
 >>> u, v, w = Decimal(11111113), Decimal(-11111111), Decimal('7.51111111')